HAVANA, Cuba -- While the angry rhetoric and bombs continue to fly back home, Colombian rebels and government negotiators in peace talks in the Cuban capital describe an increasingly collegial atmosphere and growing trust between otherwise mortal enemies.

Negotiators for the government and the Revolutionary Armed Forces of Colombia, known as the FARC, kibbutz about the latest soccer results and tease the unofficial timekeeper of the talks when it's time for a break. They share cigarettes and aromatic Cuban cigars, and even huddle around a computer screen to hash over design ideas for the website they've developed together for those seeking information about the negotiations.

Participants say it's arresting to see longtime foes who have spent the better part of half a century killing each other's friends and colleagues behaving so cordially -- and the best hope by far that they will find common ground.

Rodrigo Granda, a senior FARC commander who goes by the nom de guerre Ricardo Tellez, said the two sides "never forget that we come from opposing sides of a conflict which has not yet ended."

But he added: "There's still room for a joke, or a smile ... We have been building confidence and that is extremely important."

In interviews with The Associated Press, five participants provided the most extensive peek yet behind the curtain of the secret negotiations, which formally began in Oslo, Norway, in October and have been continuing at a convention centre in Havana ever since. In addition, the two main rebel negotiators Ivan Marquez and Rodrigo Granda have spoken publicly about the growing atmosphere of trust.

Three of the participants who spoke to AP about specific details of the talks asked not to be identified because they did not want to risk destabilizing the fragile discussions, which are centred on halting the conflict, agrarian reform, drug trafficking, victim compensation and reinsertion of the rebels into society.

There has been no agreement yet on any of the points.

This is the fourth attempt since the 1980s to bring peace to Colombia, which has been at war even since before the rebels took up arms in 1964. A U.S.-backed military buildup that began in 2000 has reduced the FARC's ranks to about 9,000 fighters and killed several top commanders, though the rebels insist they are still strong.

Building trust is particularly important in these talks, given a history of betrayal on both sides. After a political wing of the FARC laid down its arms in the 1980s, 5,000 partisans were hunted down and killed. Meanwhile, the government accuses the rebels of taking advantage of a safe haven granted in failed peace negotiations a decade ago to strengthen themselves militarily and profit from protecting the drug trade.

Colombian President Juan Manuel Santos has said the negotiations must bear fruit by November 2013 or he will call an end to the effort.

The FARC and government teams, consisting of 10 primary negotiators and about 20 support members for each side, are living in luxury houses on opposite sides of a one-time country club called El Laguito that the Cuban government now uses as a heavily-guarded official compound.

They have each others' phone numbers and often call at night to arrange details of the next day's agenda. At the meetings, both sides tap their wrists insistently to prod Jaime Avendano, a government negotiator who has become the unofficial timekeeper, when they get antsy for a break.

Participants say these 15-30 minute respites are when most informal interactions occur, with negotiators ducking out the back door of a pantry adjoining the meeting room to smoke and stretch their legs.

They talk about everything from the weather to the fortunes of Colombian soccer clubs such as Bogota's Millonarios, America of Cali and Medellin's Atletico Nacional, with sporting allegiances crossing the political boundaries.

"That's when we shoot the breeze," said one rebel negotiator at the table.

FARC and government officials also huddle in small groups with Colombian experts on land reform and other issues brought in to advise the sides, and the informal talks are a good way for both sides to hint at their positions without making formal concessions.

Former U.S. Sen. George Mitchell, a driving force behind the U.S.-brokered Good Friday peace accord in Northern Ireland in 1998, said building personal relationships can help the process, but is not enough to wipe away decades of mistrust.

"Getting to know their opponents as human beings is helpful as a predicate for getting into serious discussions," Mitchell told AP in a phone interview. "But of course it doesn't by itself resolve the differences."

Mitchell, who also served as America's Middle East envoy from 2009-2011, cautioned that familiarity does not always lead to fondness, citing the Israeli-Palestinian conflict as an example.

"When people got to know each other it validated and fortified their mistrust," he said. "Rather than liking the other side they came to dislike them even more."

Rebels in the Cuban capital say that a small core of negotiators who spent seven months in Havana earlier this year secretly laying the groundwork for the peace process sometimes socialized with their government counterparts, including at cocktails organized by Norwegian diplomats acting as guarantors. The parties also dined together in Oslo.

But no such fraternizing has occurred since the talks returned to Havana, in part because of the large size of the groups and because it has taken time for relationships to develop between the newcomers.

"Like always, at first trust had not yet been built and perhaps there was some distance, but with time the gap has been closing," the rebel's chief negotiator, Ivan Marquez, whose real name is Luciano Marin Arango, said at a Nov. 29 press conference.

Tanja Nijmeijer, a Dutch woman who joined the rebels a decade ago and is one of the only women at the negotiating table, told the AP it was "not an atmosphere among friends, but it is pleasant."

That is a striking contrast to events back home, where the declaration of a unilateral cease-fire by the FARC has not brought a halt to hostilities.

In late November a rebel front destroyed two energy towers; guerrillas later said the front had not yet received word of the cease-fire announced the previous day. A week and a half later the Colombian military bombed a cluster of FARC camps and said at least 20 guerrillas were killed.

But even through those clashes, the negotiators have had kind words to say about each other.

Multiple participants described a striking exchange between Marquez and hardline Colombian army Gen. Jorge Enrique Mora that has come to define the respect between battlefield foes helping drive the negotiations.

While the two men were talking one morning, the former Colombian armed forces chief suddenly said to Marquez: "You know, we already know each other, you and I," before rattling off the names of several battles they had fought in over the decades.

The rebel commander agreed, but added the dates of several other fierce clashes. "You didn't know I was there, but I knew you were," he quipped, breaking the tension in the room.

When asked at a press conference what it was like to face his nemesis across the negotiating table, Marquez said he respected Mora and a former national police chief as adversaries whose experiences as men of the sword would be valuable.

"They have been good at war," Marquez said. "Perhaps they know how to find the path to peace."