A Serbian government official has named the man who is currently threatening to detonate a hand grenade inside the Serbian Presidential offices as Dragan Maric.

57 year-old Maric had announced his plan in an e-mail sent to various government addresses.

Maric said in the e-mail that he would blow himself up if a court did not rule in his favor in an unspecified case by 4 pm Thursday, the official said.

"Even death is better than tyranny," he said in the e-email, according to the official, who refused to be named because she was not entitled to discuss the incident.

It is not clear whether President Boris Tadic is in the building, the BBC reported.

A media source said the man had left one grenade at the entrance to the building, on Andricev Venac Square, and gone inside "with the safety pin removed from the second".

The nearby Kralja Milana Street is reported to have been closed to traffic.

The news comes a day after US Vice-president Joe Biden became the most senior American to visit Serbia since the 1999 conflict in Kosovo.