(WARSAW) - Three thousand workers from Poland's Szczecin shipyard protested in the northwestern port on Thursday, as the European Union stepped up pressure on the government to restructure the troubled sector.

The demonstrators, carrying banners calling for their jobs to be defended, marched from the shipyard through the centre of Szczecin, and headed to the local government offices to hand over a petition demanding a meeting with Prime Minister Donald Tusk.

On Wednesday the EU's executive, the European Commission, which polices competition rules in the 27-nation bloc, had warned that Warsaw could have only until July 16 to come up with viable restructuring plans for Szczecin and two other shipyards in Gdynia and Gdansk.

Otherwise, it said, Poland could be required to recover state aid they have received.

In June 2005 the Commission began investigating 1.3 billion euros in Polish state aid paid to the yards since 2002.

EU rules on shipbuilding require such aid to be based on far-reaching restructuring plans, which must also include the participation of private investors.

The three yards risk going bankrupt if they are forced to repay the money.

The Szczecin protesters are demanding guarantees that the yards be protected from going to the wall, and that the authorities come clean about the financial situation they face.

They have also called for legal action against their former management, which they allege ruined what was a relatively healthy business compared to the yards in Gdynia and Gdansk.

Workers at Gdynia and Gdansk, which are in northern Poland, have also announced protests for Friday.

They have warned that they may block traffic in the two cities, and that they could also take to the streets of Warsaw and even head to EU headquarters in Brussels.

After several previous efforts fell through, the Polish government has been struggling to come up with restructuring plans for the yards which would satisfy Brussels.

The three yards are etched in the national mind in Poland because dozens of people were killed there when communist-era security forces fired on workers demonstrating against food price rises in 1970.

The Gdansk yard holds even greater importance for Poles because it was also the cradle of Solidarity, the trade union movement born during a strike in 1980 and which survived a 1981 crackdown before it drove the communist regime from power in 1989.

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