Members of the Communist Party-affiliated union PAME on Monday entered the Ministry of Macedonia-Thrace in Thessaloniki and hung a banner from one of the windows, calling on Greeks to join a general strike on Thursday in protest at austerity.
Around 10 members of PAME entered the building at around 7 a.m., according to local reports.
"We are fighting back. Everyone join the strike" was the slogan written on the banner.
The strike was announced last week by the country's two umbrella labor unions, GSEE and ADEDY.