A group of anarchists from the Rouvikonas group attempted to storm the Citizens Protection Ministry in Athens on Monday.
Reports say that between 20 and 30 anarchists, throwing leaflets and shouting slogans in support of the November 17 hitman Dimitris Koufondinas, entered the main courtyard of the building before they were pushed back by police.
An unconfirmed number of people have been arrested.
In a statement Rouvikonas said the action was in response to the Greek authorities’ refusal to grant Koufondinas leave.
The convicted terrorist is currently serving a number of life sentences for crimes including murder and has been seeking more prison leave after a pair of two-day releases earlier this year.
However, the previous furlough had sparked anger from victims’ families.