Thousands of demonstrators staged an anti-austerity march in London on Saturday, in the first major public protest since Conservative Prime Minister David Cameron won a general election.

Opposition politicians, trade union bosses and celebrities were among the crowds marching through the capital's financial district.

Protesters called for the halting and reversal of spending cuts imposed by the previous coalition government and further measures proposed by finance minister George Osborne.

"We have seen a huge impact on our work at primary school," said Sian Bloor, 45, a teacher from Trafford near Manchester.

"I regularly bring clothes and shoes for children and biscuits for their breakfast, just so they get something to eat. You can see how children are being affected by the cuts." Bloor said.

Placard-waving protesters marched from the Bank of England and filed past the nearby Royal Exchange, as the sound of drummers filled the air, creating a festival atmosphere.

Some of the placards read: "Austerity Doesn't Work", "No to Cuts", "Get the Tories Out" and "Austerity is Class War".

"It will be the start of a campaign of protest, strikes, direct action and civil disobedience up and down the country," said Sam Fairbairn of organisers the People's Assembly.

"We will not rest until austerity is history, our services are back in public hands and the needs of the majority are put first." Fairbairn said.

Cameron clinched an unexpected election victory on May 7 that gave his centre-right Conservative party an outright majority in parliament for the first time in nearly 20 years.

The victory was widely seen as an endorsement of the Conservatives' austerity programme and is likely to see a continuation of cuts to public spending as they seeks to curb a budget deficit of nearly $140 billion.

The Conservatives had already implemented swinging cutbacks in public services and welfare spending during the previous coalition administration with the centrist Liberal Democrats.

Organisers are seeking on Saturday to highlight the impact of previous cutbacks on public services, the state-run National Health Service (NHS), welfare and education.

They will also warn over the effects of new austerity measures that Osborne is expected to unveil in a new budget on July 8.

Source: Agencies