A bomb disguised as a gift has killed an aide to the Greek cabinet minister in charge of the country's police.
The victim, George Vassilakis, adjutant to the minister, was a father of two children.
No one immediately claimed responsibility for the blast, on the seventh floor of the ministry that caused serious damage to the office of Civil Protection Minister Mihalis Chrysohoidis.
He said: "The cowardly murderers will be brought to justice, to be tried in accordance with the constitution and our laws. I lost a valuable and dear colleague."
Police spokesman Thanassis Kokkalakis said: "It was a wrapped package that exploded in the aide's hands after he apparently picked it up and tried to open it. We heard a big bang, there was a lot of smoke and damage".
Greece has been rocked by a series of bomb attacks claimed by leftist militants since its worst riots in decades in 2008. Earlier this year, Greece arrested six suspected members of the country's most militant group, Revolutionary Struggle.
When he took office in 2009, Chrysohoidis said that he would crack down on militants. In a previous spell in the job in 2002, he dismantled November 17, Greece's most lethal guerrilla group.