YANGON, Myanmar - Police in Myanmar escalated their crackdown on demonstrators against this month's military takeover, deploying early and in force on Saturday as protesters sought to assemble in the country's two biggest cities and elsewhere.

Security forces in some areas appeared to become more aggressive in using force and making arrests, utilizing more plainclothes officers than had previously revealed themselves. Photos posted on social media showed that residents of at least two cities, Yangon and Monywa, resisted by erecting makeshift street barricades to try to hinder the advance of the police.

Myanmar's crisis took a dramatic turn on the international stage at a special session of the United Nations General Assembly on Friday when the country's U.N. ambassador declared his loyalty to the ousted civilian government of Aung San Suu Kyi and called on the world to pressure the military to cede power.

There were arrests Saturday in Myanmar's two biggest cities, Yangon and Mandalay, where demonstrators have been hitting the streets daily to peacefully demand the restoration of the government of Suu Kyi, whose National League for Democracy party won a landslide election victory in November. Police have increasingly been enforcing an order by the junta banning gatherings of five or more people.

Many other cities and towns have also hosted large protests against the Feb. 1 coup.

Police in Dawei, in the southeast, and Monywa, 135 kilometres (85 miles) northwest of Mandalay, used force against protesters. Both cities, with populations of less then 200,000 each, have been seeing large demonstrations.

Social media carried unconfirmed reports of a protester shot dead in Monywa. The reports could not immediately be independently confirmed but appeared credible, with both photos and identification of the victim, though later accounts said the woman had not died. The reports from Monywa also said dozens or more people were arrested.

The military takeover reversed years of slow progress toward democracy after five decades of military rule. Suu Kyi's party would have been installed for a second five-year term in office, but the army blocked Parliament from convening and detained her and President Win Myint, as well as other top members of her government.

At the General Assembly in New York, Myanmar's U.N. ambassador, Kyaw Moe Tun, declared in an emotional speech to fellow delegates that he represented Suu Kyi's “civilian government elected by the people” and supported the fight against military rule.

MRTV, a Myanmar state-run television channel, broadcast an announcement Saturday from the Foreign Ministry that Kyaw Moe Tun has been dismissed from his post because he had abused his power and misbehaved by failing to follow the instructions of the government and betraying it.

Kyaw Moe Tun had urged all countries to issue public statements strongly condemning the coup, and to refuse to recognize the military regime. He also called for stronger international measures to stop violence by security forces against peaceful demonstrators.

He drew loud applause from many diplomats in the 193-nation global body, as well as effusive praise from other Burmese on social media, who described him as a hero. The ambassador flashed a three-finger salute that has been adopted by the civil disobedience movement at the end of his speech in which he addressed people back home in Burmese.

In Yangon on Saturday morning, police began arrests early at the Hledan Center intersection, which has become the gathering point for protesters who then fan out to other parts of the city. Police took similar action in residential neighbourhoods.

Security forces also tried to thwart protests in Mandalay, where roadblocks were set up at several key intersections and the regular venues for rallies were flooded with police.

Buddhist monks were prominent in Saturday's march in Mandalay, as they have been regularly, lending moral authority to the civil disobedience movement that is challenging the military rulers.

Mandalay has been the scene of several violent confrontations, and at least four of eight confirmed deaths linked to the protests, according to the independent Assistance Association of Political Prisoners. On Friday, at least three people there were injured, including two who were shot in the chest by rubber bullets and another who suffered what appeared to be a bullet wound to his leg.

According to the association, as of Friday, 771 people had been arrested, charged or sentenced at one point in relation to the coup, and 689 were being detained or sought for arrest.

The junta said it took power because last year's polls were marred by massive irregularities. The election commission before the military seized power coup had refuted the allegation of widespread fraud. The junta dismissed the old commission's members and appointed new ones, who on Friday annulled the election results.

Associated Press writer Edith Lederer at the United Nations contributed to this report.