ATHENS, May 25 (Reuters) - Greece's anti-terrorism squad was investigating on Sunday an apparent attack at the headquarters of the co-ruling Socialist PASOK party after two bullets pierced its windows, police said.
Greeks began voting in a second round of local and European Parliament elections on Sunday, seen as a litmus test for support for Prime Minister Antonis Samaras's shaky government.
The attack on PASOK's offices, in a bustling central Athens neighbourhood packed with bars and cafes, was likely carried out overnight, said a police official who declined to be named. Its offices are guarded around the clock by police in riot gear.
"Two office windows on the second and third floor have been hit by a firearm. The anti-terrorism unit has taken over the investigation," Greek police said in text message to journalists, without giving further details.
Police cordoned off the area and more than two dozen riot policemen were at the scene on Sunday afternoon.
"There is no way we will be terrorised," PASOK lawmaker Odyseas Konstantinopoulos, the party's spokesman, told Reuters of the attack.
PASOK backs Samaras' conservative New Democracy party in a coalition that has enforced harsh austerity measures, including drastic cuts to wages and pensions, in return for bailouts totalling 240 billion euros ($327 billion) from the European Union and International Monetary Fund.
The once-mighty party, which won a landslide election victory with 44 percent of the vote in 2009, has seen its support hover at around 6 percent in opinion polls.
Attacks against politicians, journalists and businessmen have been on the rise in Greece in recent years as it struggles through a six-year economic depression and record unemployment. ($1 = 0.7336 Euros) (Reporting by Renee Maltezou and Karolina Tagaris; Editing by Raissa Kasolowsky)