Kosovo's president is alleging that senior Serb officials are responsible for the 1999 slayings of three Albanian-American brothers who fought with ethnic Albanian fighters against Serbia's rule.

Hashim Thaci on Tuesday met in Pristina with Ilir Bytyci, brother of Ylli, Mehmet and Agron Bytyci, whose bodies were found in a mass grave in Serbia in 2001.

Thaci says Bytyci's killers "are positioned at the highest institutions of the state of Serbia," pledging Pristina will increase pressure to clarify the circumstances of their deaths and bring the perpetrators to justice.

Kosovo's 1998-99 war for independence ended with a 78-day NATO air campaign. The U.N. then ran Kosovo until its 2008 declaration of independence, which is recognized by 116 countries, but not by Serbia.

Some 10,000 people died and 1,660 remain missing.