Greece's public order minister escaped injury after a bomb went off next to his office Thursday, killing a close aide, police said, dpa reported.
The bomb, a booby-trapped package disguised as a gift, exploded in the seventh-floor office of Civil Protection Minister Michalis Chrysohoidis' chief of staff, causing extensive damage.
The minister was reportedly in his office at the time of the blast, but was not injured.
"A father of two died today - we will not stop our fight to protect and serve the Greek citizen," said Chrysohoidis. "Those responsible will be brought to justice."
No one immediately claimed responsibility for the blast, which took place in one of the most heavily guarded buildings in the country.
Police told the German Press Agency dpa that the officer opened the suspicious package that contained the bomb. It was not clear how the package had been delivered.
Authorities immediately sealed off the building and blocked off traffic in front of the ministry, which is located along a busy street near downtown Athens.
The blast shattered windows throughout the ministry and could be heard several kilometres away.
Greece has been hit by a series of bomb attacks by leftist militant groups since the country's worst riots took place following the police shooting of a teenager in 2008.
Chrysohoidis vowed to crack down on anarchists and militants when he took office in October 2009.