Kosovo's parliament building was damaged in a blast late Thursday, state television RTK reported.
The explosion, apparently a grenade, hit the second floor of the building, which was empty at the time of the attack, the report said, quoting police.
Hours earlier, Prime Minister Isa Mustafa's cabinet sent a controversial border agreement with Montenegro to the legislature for debate. The nationalist opposition is strongly against the agreement.
Over the past year, the opposition has repeatedly fired tear gas in parliament and held street protests in attempts to block the border agreement along with a deal on expanded rights for minority Serb communities.
Kosovo is a former Serbian province with a mostly Albanian population. It gained independence in 2008, nine years after a war on its soil drew NATO to intervene against Serbia.
The young country remains volatile and plagued with problems - from high-level corruption to ethnic tensions to rampant unemployment - despite billions of dollars that the European Union and the international community have pored into missions assisting it.