ATHENS, Greece—Greece's main labor unions have called a general strike for Oct. 18, the day of a European Union summit and a month after a similar strike saw tens of thousands demonstrate and violent clashes break out with police.

The government has been struggling to come up with (EURO)13.5 billion ($17 billion) worth of austerity measures for 2013-14 so it can qualify for its next rescue loan payment. Without the money, Greece would run out of funds next month.

The government hopes to have an agreed package for the summit.

Greece has been dependent on bailouts from its euro partners and the International Monetary Fund since May 2010. In return, it enacted deep budget cuts and tax hikes.

The unions said Wednesday that the "barbaric measures" are leading to poverty.