NAIROBI, Kenya -- In an extraordinary public statement only days before Kenya's high-tension national election, the country's chief justice on Wednesday said he has received a threatening letter warning of dire consequences if the judiciary doesn't allow a top candidate indicted by the International Criminal Court to run.

Chief Justice Willy Mutunga also revealed that an immigration officer at Nairobi's airport tried to prevent him from travelling to Tanzania on Tuesday in what Mutunga said was a likely a political act.

Kenya on March 4 goes to the ballot box for the first time since a flawed presidential election in late 2007 devolved into mass violence that killed more than 1,000 people. The government, international observers and foreign governments have been making efforts to ensure this year's vote is not marred by violence.

Fears are high, though. A pre-election meeting hosted by the United States Embassy on Monday attracted more than 500 Americans to the ambassador's residence, where U.S. citizens heard what precautions they should take in case violence breaks out. The embassy told the gathered Americans that violence is possible but that overall it expects a peaceful vote.

Threats are circulating. A letter dated Feb. 13 addressed to judges and ambassadors said that the judiciary should not prevent Uhuru Kenyatta -- one of two top candidates for president -- from running for office. The letter began circulating just before Kenya's High Court last week ruled that it had no jurisdiction to determine whether Kenyatta, the deputy prime minister, and former government minister William Ruto -- Kenyatta's running mate -- can run for the country's top offices.

The two face crimes against humanity charges at the International Criminal Court for allegedly orchestrating violence after Kenya's 2007 election in which more than 1,000 people were killed. The U.S. and European nations have warned that their relations with Kenya will be affected if Kenyatta is elected.

The Feb. 13 letter said that if Kenyatta is stopped from running then the judges and ambassadors should "buy your own coffins and graves. We will cut off your heads and feed them on wild animals in Nairobi National Park."

"We are tired of being bullied by America, Britain and the European Union. We know your boss the chief Justice is a stooge of the American," the letter said.

The letter is attributed to the Mungiki -- a powerful Kenyan gang -- but the veracity of the letter has not been confirmed.

Mutunga said the letter and the airport incident were indicative of a pattern of emerging harassment against him and other judges. He said that at least five judges have been attacked in recent days, with some attacks involving gun violence.

"If anybody, any candidate, any party, any agency, or any other actor thinks that it will bend the ear, mind and resolve of this Chief Justice to do anything that is unconstitutional or illegal, then they are mistaken," Mutunga said. "On any matter that will come before me or the Supreme Court, I and the Court shall operate strictly within the confines of the Constitution. Intimidation and threats are uninvited guests and will not be hosted in the execution of our mandate."

Mutunga said that after being held back by immigration officers at the Nairobi airport, he was able to board his plane and landed in Tanzania, where he received a call from Kenya's director general of the National Intelligence Service apologizing for a "small hiccup" at the airport. Mutunga said he told the director general that he believed he was the victim of deliberate harassment and that a public accounting is required.

Mutunga in his statement appealed to Kenyans to hold a peaceful vote.

"It is only by so doing that we shall silence these dark forces of retrogression and also advance our constitutional and democratic promise," he said.