* Brown wishes he'd done more, takes full responsibility
* Poll ratings boosted after G20 finance ministers meeting
(Adds reaction, opinion poll)
By Keith Weir and Kate Holton
LONDON, March 17 (Reuters) - British Prime Minister Gordon Brown, lagging in opinion polls, said on Tuesday he wished he had done more to impose better regulation earlier and took full responsibility for his role in the economic crisis.
In an interview with the Guardian newspaper, Brown did not rule out a further economic stimulus in April's budget and said the pure free-market era was over.
Brown, finance minister for a decade under Tony Blair until he became prime minister in 2007, has faced repeated calls from the media and opposition politicians to apologise for not seeing the economic downturn earlier.
"I take full responsibility for all my actions," he said. "But I think we're dealing with a bigger problem that is global in nature, as well as national," he told the newspaper, under the headline 'I should have done more to prevent bank crisis'.
The comments echoed Brown's standard line that the economic crisis, which has pushed Britain into recession for the first time since the early 1990s, is not a home-grown phenomenon.
Opposition Conservatives called his response inadequate.
"This shows that Gordon Brown doesn't understand the depth of the problems we face," said Conservative finance spokesman George Osborne. "He is neither acknowledging what he himself got wrong nor apologising for his role in the fundamental failure of his whole economic model."
Brown, who will host a G20 summit of world leaders on the financial crisis in London next month, said tougher regulation should have been introduced to regulate financial markets.
"Perhaps 10 years ago after the Asian crisis when other countries thought these problems would go away, we should have been tougher ... keeping and forcing these issues on to the agenda like we did on debt relief and other issues of international policy."
POLL BOOST
There was some good news for Brown on Tuesday when an opinion poll showed his ruling Labour Party had halved the Conservatives' ratings lead. The Ipsos MORI poll put Labour on 32 percent, four percentage points up on last month, with the Conservatives down six on 42 percent.
Brown is hoping that a successful G20 summit will help to boost his ratings and set Labour on course for a fourth successive victory in an election due by mid-2010.
However, analysts were sceptical about the impact of meetings like the G20 on domestic poll standings.
"I don't think ordinary members of the public are very impressed by these international photo opportunities when they see people losing their jobs around them," said Wyn Grant, a professor of politics at Warwick University in central England.
Figures due out on Wednesday are expected to show unemployment rising above 2 million for the first time since shortly after Labour came to power in 1997.
The Bank of England has cut interest rates and the government has launched a series of measures to boost the economy, but Brown has said it will take time for them to work.
Brown said 40 years of free-market orthodoxy had come to an end. "Laissez-faire has had its day," he said.
The centre-left "should be confident enough to say that the old idea that markets were by definition efficient and could work things out themselves is gone." (Additional reporting by Peter Griffiths, editing by Kate Kelland and Mark Trevelyan)