LONDON Anti-austerity protesters marching in London on Saturday should explain what alternative they would offer in place of the government's deficit reduction plan, Deputy Prime Minister Nick Clegg said.
Union leaders have called the demonstration to oppose deep state spending cuts, public sector job losses, tax rises and pension reforms.
"The people who scream and shout against this government, they have to come up with an answer, what would they do (about the economy)," Clegg told Reuters in an interview late on Friday.
His Liberal Democrat party has slumped in opinion polls as former supporters abandon it for joining a Conservative-led government committed to virtually eliminating a record budget deficit by 2015.
The coalition blames the former Labour administration for Britain's economic difficulties and Clegg said Labour was being dishonest about its own plans for the deficit.
Labour leader Ed Miliband is expected to address protestes when they gather at the end of the march in Hyde Park.
"If I was a demonstrator in London, I would be furious with the Labour leadership, because they are whipping up people's fervour and they are being utterly dishonest," said Clegg.
"They have a secret plan of their own of 14 billion pounds' worth of cuts next month and they won't even level with people about where those cuts will fall.
"Have they told their trade union paymasters, have they told the demonstrators, that Labour is now the only party that wants to go into the next general election advocating three more years of cuts?"
Labour says the deficit soared because of the global financial crisis and that the government risks strangling economic recovery by cutting the deficit too fast.
It would reduce the deficit at a slower pace, aiming to halve it by the time of the next election in 2015 from its current level of around 10 percent of GDP.
Clegg conceded the austerity programme was unpopular but said the government was being open with voters.
"At least we have a clear plan, we are being candid with people about what that involves," he said.
"We have an opposition party that has retreated into the worst kind of infantile opposition politics, which is to score lots of tactical points and not level with people about what they would do instead."