(Recasts with speech)

By Adrian Croft

MANCHESTER, England, Sept 28 (Reuters) - Britain's newopposition leader said on Tuesday economic policy should focuson growth, not just cutting the budget deficit, and he would notsupport irresponsible strikes against planned spending cuts.

Labour Party leader Ed Miliband, 40, set out in his firstspeech to the party's annual conference to tackle concerns thathe would be lax on cutting the deficit or would be a left-wingerin the pocket of the trade unions.

Labour was ejected from power after 13 years in May'selection, replaced by a Conservative-Liberal Democrat coalitionthat plans deep spending cuts to reduce a record peacetimebudget deficit left behind by Labour.

"I won't oppose every cut the coalition proposes," Milibandtold the conference in the northwestern city of Manchester.

"And come the next election there will be some things theyhave done that I will not be able to reverse," he said.

Miliband surprisingly beat his older brother David to becomeLabour leader on Saturday thanks to strong union support,prompting accusations he would be beholden to the unions.

"I have no truck, and you should have no truck, withoverblown rhetoric about waves of irresponsible strikes. Thepublic won't support them. I won't support them. And youshouldn't support them either," he said in his speech.

With public concern about the impact of cuts growing, Labouredged ahead of the centre-right Conservatives for the first timein three years in a YouGov opinion poll published in the Sunnewspaper on Tuesday.

SERIOUS ABOUT DEFICIT

Miliband said he was serious about reducing the deficit.

"But what we should not do as a country is make a badsituation worse by embarking on deficit reduction at a pace andin a way that endangers our recovery," he said.

"The starting point for a responsible plan is to halve thedeficit over four years, but growth is our priority and we mustremain vigilant against a downturn," he said.

Without a plan for growth, there would be no credible planfor deficit reduction, he said.

Labour fought the election on proposals to halve the deficitin four years, less ambitious than coalition plans to virtuallyeliminate the deficit by 2015, when the next election is due.

Miliband has said the era of "New Labour" -- former PrimeMinister Tony Blair's brand of centrist, business-friendlypolitics that won him three elections -- is over.

But he rejected the "Red Ed" nickname he has been given bysome newspapers. "Come off it," he said.

He signalled a break with some of the party's policies, anddistanced himself from former Prime Minister Gordon Brown'sstewardship of the economy.

Brown, weakened by a banking meltdown and a deep recession,quit after Labour lost the May election.

"When you saw the worst financial crisis in a generation, Iunderstand your anger that Labour hadn't stood up to the oldways in the City (financial district), which said deregulationwas the answer," said Miliband, who was a confidant of Brown.