(GDYNIA) - Thousands of workers at Poland's main shipyards downed tools on Friday and called on the government to defend their jobs amid fears an EU ruling could bankrupt their industry.

On the Baltic Sea coast more than 2,000 workers rallied at the headquarters of the Gdynia shipyard under banners of Poland's historic Solidarity trade union.

Protesters called in a petition on President Lech Kaczynski and Prime Minister Donald Tusk to "take strong measures to save Poland's shipyard industry, including the Gdynia yard, to save thousands of jobs."

Some 200 workers from neighbouring Gdansk travelled to nearby Sopot to demonstrate at Tusk's home later on Friday and were met by a heavy police presence.

The largest demonstration was in the northwestern port of Szczecin where 3,000 workers from another threatened yard downed tools.

The European Commission, which polices competition rules in the 27-nation bloc, said on Friday it would study "very quickly" an update on Polish plans to save the yards and aimed to reach a decision by the start of next week.

Spokesman Jonathan Todd said Brussels "has been trying to find a positive outcome for the shipyards for four years" and nobody could accuse it of "not having given very ample opportunities" to ensure their future.

On Wednesday the Commission gave Warsaw 24 hours to produce restructuring plans for Szczecin, Gdynia and Gdansk, the cradle of the iconic 1980s anti-communist movement Solidarity.

The Commission said Friday that Warsaw had provided "new information" concerning the restructuring of three shipyards hours before the midnight deadline.

EU rules only allow state aid to be paid to shipyards if it is accompanied by meaningful restructuring plans aiming to make them economically viable, rather than simply keeping them afloat with public money.

The Commission has said that unless Polish authorities produce viable restructuring plans it will have to consider state aid to the yards as illegal.

That would leave it little choice but to order the government to recover past aid from the shipyards, which could bankrupt them.

The Commission has warned it could issue an order as soon as July 16.

On Thursday the Polish government had pleaded for more time.

"We will be able to satisfy the demands of the European Commission... if we have until the end of September to negotiate privatisation agreements with investors," Treasury Minister Aleksander Grad told reporters.

In June 2005, the Commission began investigating 2.1 billion euros (3.3 billion dollars) in Polish state aid paid to the yards since 2002. Warsaw insists the sums were far lower.

The three yards and their subcontractors employ a total of 60,000 people.

The sites are etched in the national consciousness because dozens were killed there when communist-era security forces fired on workers demonstrating against food price rises in 1970.

The historical role of the Gdansk yard is even greater for Poles: Solidarity was born there during a strike in 1980, survived a 1981 crackdown, and drove the communist regime from power in 1989.

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