By Edmund Blair and Patrick Nduwimana
BUJUMBURA (Reuters) - A top U.S. diplomat was heading to Burundi on Wednesday, seeking to halt escalating unrest triggered by President Pierre Nkurunziza's decision to seek a third term in office, a move protesters say is unconstitutional.
Since Sunday, police in the landlocked nation at the heart of Africa have clashed with protesters who say Nkurunziza's plan to run again in the June 26 election threatens the Arusha peace deal that ended an ethnically fueled civil war in 2005.
"On my way to Burundi. Disappointed President Nkurunziza violating Arusha Accord," Tom Malinowski, U.S. assistant secretary of state for democracy, human rights and labor, wrote on his Twitter feed, adding it was not too late for the leadership and people to keep a "peaceful democratic path".
On Tuesday, the government told ambassadors at a meeting in Burundi, including the U.S. envoy, to stay neutral and said some were showing "a lot of sympathy" with protest organizers.
Police say two people have been killed. Civil society groups say the death toll is five. Scores more have been injured and arrested.
About 25,000 people have fled across the border fearing a resurgence of ethnic killings. The civil war pitted the army, then led by the ethnic Tutsi minority, against rebel groups of majority Hutus. The army is now fully mixed.
For now, diplomats say the conflict is a power struggle not an ethnic tussle. The opposition includes coalitions of Hutus and Tutsis.
But they say escalating violence could reopen old wounds and trigger ethnic bloodletting. Refugees, many of them Tutsis, who have fled to Rwanda say the ruling party's Imbonerakure youth wing has threatened them, a charge the party denies.
The government has shown no public sign of changing tack. It says the opposition wants to disrupt elections it can't win. It says Nkurunziza's can run again because his first term, when he was picked by lawmakers not elected does not count.
The constitution and Arusha deal set a two-term limit.
The United States, other Western nations and African countries have pushed Nkurunziza to step aside. Washington said it would take steps against those behind any violence.
One senior Western diplomat said the government had been expected to talk tough in Tuesday's meeting but the test would be whether it showed in flexibility in private.
"We still have to fight to get some way of organizing some kind of dialogue to try to calm down," he said.
(Additional reporting by George Obulutsa in Nairobi; Writing by Edmund Blair; Editing by Andrew Heavens)