BUJUMBURA, Burundi (AP) — The U.S. envoy to Africa's Great Lakes region on Tuesday urged Burundi's government and the opposition to start internationally mediated talks without pre-conditions in order to end the country's political crisis.

Tom Perriello told reporters in the Burundian capital, Bujumbura, that the international community is keenly watching events in Burundi, where a series of extrajudicial killings has raised concern.

A regional bloc nominated Ugandan President Yoweri Museveni to mediate the crisis but the talks have not started.

Perriello is visiting Burundi to express Washington's "grave concerns" over the deteriorating political situation in Burundi, which has been hit by violence since April following the president's controversial decision to seek a third term in office.

"The United States is alarmed by the violent and incendiary language used by the Burundian government as well as the violence by the security forces and security personnel or by anti-government actors," he said.

At least 240 people have been killed since April, according to the U.N.

Last week President Pierre Nkurunziza urged the security forces to use all means necessary to restore order. But many residents charge it is the security forces that are carrying out the killings. Burundi's security forces are currently disarming parts of Bujumbura, an exercise that has been marred by violence. The police have been accused of unfairly targeting some people, and many residents have fled their homes fearing they will be framed and jailed.

Although the current violence appears to be political, Burundi has a history of deadly conflicts between the country's Hutu and Tutsi ethnic groups.

Nkurunziza took power in 2005 near the end of a civil war in which some 300,000 people were killed between 1993 and 2006.