Prime Minister Aleksandar Vucic will visit Washington with new evidence in the case of the murder of the Bytyqi brothers.

Serbian War Crimes Prosecutor Vladimir Vukcevic also told Radio Belgrade that authorities have been intensively working on the case and that the FBI has participated in the investigation since the beginning.

Vukcevic said this case should be closed along with others by the end of his mandate.

Vucic will travel to the U.S. in mid-September and meet with U.S. Vice President Joseph Biden. The case of the murder of the brothers - U.S. citizens of Albanian origin - is expected to be one of the topics.

Vucic last month said the case was a big bilateral problem between Belgrade and Washington.

The brothers have had crossed into then Federal Republic of Yugoslavia illegally from Albania and joined the so-called Atlantic Brigade of the KLA.

They were killed in July 1999 in a police range in Petrovo Selo, shortly after the end of the war in Kosovo.

The bodies of Agron (23), Mehmet (21) and Illy (25) Bytyqi were found in 2001 in a mass grave near Petrovo Selo along with the bodies of 67 more men and seven women.