POLICE fired tear gas at thousands of protesters who rallied in central Frankfurt to voice growing European discontent against tough austerity measures that have been applied across the continent over the debt crisis.

No injuries were reported but the march towards the European Central Bank (ECB) was halted several several times because of the tear gas.

The demonstration in Germany, coinciding with the ECB's 15th anniversary, was matched later by similar rallies in both recession-hit Spain and Portugal.

Police estimated that 7,000 people took part in the protest. Organisers had targeted a turnout of 20,000 but were unable to estimate the actual numbers.

"We would clearly like to say that the policies of the European Central Bank and the troika ... are not the solution," said Roland Suss, a spokesman for the Blockupy movement that organised the demonstration.

The troika of international lenders -- the International Monetary Fund, the European Union and the European Central Bank -- have imposed strict conditions on countries such as Greece and Portugal in exchange for bailout funds.

Protesters say the belt-tightening measures applied by many governments to try to meet the conditions unfairly penalise the poor as some governments have been forced to slash jobs and raise taxes.

Sixty-two-year-old Marica Frangakis from Greece said: "I'm from the baby boom generation, and we have had a relatively good life. But now we have to fight for our survival."

In Greece, people "are desperate after the five-year crisis", she said, adding that "it's good to see that people (in Germany) also feel concerned about the crisis."