More than 200 employees of a Greek shipyard on Thursday broke into thecourtyard of the defence ministry in Athens to protest against non-payment of their wages, police said.

They broke down barriers at the entry and anti-riot forces were sent in half an hour later using clubs and tear gas to remove them. When they refused to leave they were arrested en masse.

The chief of staff had earlier tried to speak to them but was shouted down with cries of "Thieves! Thieves!", images on television showed.

Defence Minister Panos Panayotopoulos, who was at an official ceremony at the port of Piraeus as the incident began, let it be known he would meet the demonstrators on condition they left the ministry.

The protest briefly blocked traffic on a busy major thoroughfare where the ministry is located.

The demonstrators said they had not been paid for several months while their place of work, Hellenic Shipyards, at Skaramangas in the industrial suburbs of Piraeus, was threatened with bankruptcy.

It was sold in 2010 by its previous owners, the German industrial conglomerate ThyssenKrupp, to the Abu Dhabi Mar group, but has been operating at less than capacity for months as it depends on modernisation contracts from the Greek armed forces, which have been suspended or delayed due to Greece's financial crisis.

Ongoing austerity cuts and reforms to make the Greek economy more competitive have caused waves of strikes and protests, many of them violent.

Also on Thursday, around 1,000 farmers on the island of Crete tried to storm the runway of Heraklion airport and clashed with police.

The farmers, who were pushed back with tear gas, were protesting against lower tax returns and higher insurance contributions.

Doctors and nurses at public hospitals also demonstrated on Thursday at the health ministry in Athens against pay and budget cuts planned in the latest round of austerity measures, the fourth since 2010. The government is negotiating these measures with its creditors: the European Union, the European Central Bank and the International Monetary Fund.

The planned adoption of the new austerity measures has led to an increase in social tensions, but the EU and the IMF have made continuing financial aid conditional on them.