About 5,000 Poles protested in Warsaw on Tuesday against closer European integration after the government agreed to a new EU treaty for closer fiscal cooperation to tackle economic crisis.

The protesters waved Polish flags and at one point chanted Disgrace! during the rally organised by the main opposition, the conservative, euro-sceptic Law and Justice (PiS) party.

The peaceful demonstration took place on the 30th anniversary of a crackdown by communist authorities against the pro-democratic opposition lead by the Solidarity trade union.

As he addressed the crowd, PiS leader Jaroslaw Kaczynski drew a parallel between the 1981 Poland's subjugation under the Martial Law to the Soviet Union and the current government's support for deeper EU integration.

PiS will lead the fight for a truly sovereign Poland where Poles themselves can decide on what is most important for them, can build their prosperity on their own, because we can afford that, he said.

Poland, the largest former communist state in the EU, is still outside the euro zone and has so far avoided the recession engulfing much of the 27-nation bloc.

Kaczynski accused Prime Minister Donald Tusk's government of betraying the nation's interests by giving Germany whip hand in the EU, to the cheers of the crowd.

Tusk, at the helm of a centrist, pro-business party, believes deeper EU integration is essential to Poland's security and prosperity. PiS and other euro-sceptic parties have accused him of surrendering the country's hard-won independence.

But, partially thanks to Poland's still-resilient economy, PiS and other euro-sceptic parties have, until now, failed to make political capital from the current European malaise.

This is not the appropriate time for some Poles to play people off against each other, Tusk told a news conference on Tuesday, referring to the still-divisive Martial Law issue.

Some 44 percent of Poles believe declaring the state of emergency was right, while 34 percent believe it was wrong, according to a recent survey by CBOS pollster.

This is an anniversary that should make us reflect on the obligations and the limits of power, both in the communist times as well as today, he said. The memory of these events should unite us.

(Reporting by Gabriela Baczynska; Editing by Alessandra Rizzo)