By Edmund Blair and Patrick Nduwimana
BUJUMBURA (Reuters) - A senior U.S. diplomat arrived in Burundi on Wednesday to try to help halt escalating unrest and defuse the country's biggest crisis in years, set off by President Pierre Nkurunziza's decision to seek a third term.
Police in the east African nation have clashed for four days with protesters who say Nkurunziza's plan to run again in the June 26 election violates the constitution and threatens a peace deal that ended the ethnically fuelled civil conflict.
Before arriving, Tom Malinowski, U.S. assistant secretary of state for democracy, human rights and labor, wrote on Twitter: "Disappointed President Nkurunziza violating Arusha Accord." He added it was not too late for a "peaceful democratic path."
In response, presidential media adviser Willy Nyamitwe told Reuters: "This is not neutral, but we are in a democratic process and anyone is free to have his own point of view."
A senior State Department official said U.S. concerns about Nkurunziza's decision to seek a third term had been raised with government officials in Burundi and in the region.
In meetings, U.S. Ambassador to Burundi Dawn Liberi had also raised concerns over the closure of independent media outlets and pressed for dialogue between the government and opposition to "establish a credible and inclusive electoral process," the official added.
The U.N. Security Council expressed concern on Wednesday about the escalation of hostilities and restrictions on freedom of expression and assembly. It urged all parties to refrain from violence and intimidation.
The streets of the capital, Bujumbura, were calmer on Wednesday. Police fired tear gas when protesters approached them, but both sides mostly kept behind makeshift barricades of stones, smoldering tyres and sticks.
"I want to fight for the right of people, and I reject the third term that the president is taking by force," said Innocent Miturizo, 27, a student in a suburb that has seen regular protests.
Said Djinnit, the U.N. Special Envoy for the Great Lakes region, met Nkurunziza on Monday. Djinnit was in Burundi to ensure there was space for dialogue, the United Nations said.
Police say two people have been killed in this week's violence. Civil society groups say the death toll is five. Scores more have been injured and more than 250 arrested.
About 25,000 people have fled across the border fearing a resurgence of ethnic killings.
The 12-year civil war pitted the army, then led by the ethnic Tutsi minority, against rebel groups of majority Hutus. The army is now fully mixed, while the opposition includes coalitions of Hutus and Tutsis.
Diplomats say escalating violence could reopen old wounds and trigger ethnic bloodletting.
The constitution and Arusha peace accords set a two-term limit, but Nkurunziza's supporters say he can run again because his first term, when he was picked by lawmakers and not elected, does not count.
The African Union's Peace and Security Council on Wednesday said both sides should await Burundi Constitutional Court's decision on his eligibility.
(Additional reporting by George Obulutsa in Nairobi, Michelle Nichols in New York and Lesley Wroughton in Washington; Writing by Edmund Blair and Drazen Jorgic; Editing by Tom Heneghan and Jonathan Oatis)