UPDATE 1-Real Doha trade talks must start now-U.S.

* U.S. says now or never for Doha trade talks

* Seeks moves from China, India, Brazil (Adds details, background, byline)

By Jonathan Lynn

GENEVA, Jan 13 (Reuters) - Trading powers must get down to real negotiations right away if there is to be any hope of concluding the long-running Doha talks to open up global commerce this year, a top U.S. negotiator said on Thursday.

To reach a deal, said the U.S. ambassador to the World Trade Organization (WTO) Michael Punke, big emerging countries like China, Brazil and India should accept that their booming economies meant they must open up their markets more.

WTO members have drawn up a programme of intensive talks for the next few weeks, after leaders of the G20 rich and emerging economies called for the Doha round to be finished and said 2011 was a window of opportunity.

Economists say a Doha agreement could boost the world economy by hundreds of billions of dollars. But the nine-year-old talks have repeatedly missed deadlines and many negotiators are sceptical a deal is possible now as countries are wary of opening up their markets if that endangers jobs.

Punke said the complex negotiations would require so much detailed work that a deal could not be done unless the real give and take of bargaining over substantive issues starts now.

"For 2011 to be a window of opportunity we have to all be negotiating effective immediately. That's the logistical reality of the Doha negotiations," he told a briefing.

"There's an awful lot of work to be done."

DISAPPOINTING CONTACTS

Talks next week on agriculture and industrial goods -- the core issues in the Doha talks -- would show whether Washington's partners were really willing to deal, he said.

A meeting of key trade ministers at the World Economic Forum in the Swiss resort of Davos at the end of this month would not yield a substantive breakthrough but would allow countries to signal whether they were serious about the talks, he said.

Punke said recent contacts with China had been disappointing as they had not gone into the detailed negotiations the United States had looked for.

The United States had given China a detailed list of products where it was seeking better access, but at talks in Washington in December China did not respond, he said.

However, it was encouraging that Commerce Minister Chen Deming indicated to U.S. Trade Representative Ron Kirk that it would consider sectoral deals -- a long-standing U.S. demand.

In sectoral deals, groups of participating countries would go beyond any overall tariff cuts agreed by the WTO's 153 members to eliminate duties in certain industrial sectors.

Washington believes such deals, for instance in chemicals, are essential to open up world trade, but emerging countries have reservations.

Punke said China was now the world's second biggest producer of chemicals and fifth biggest exporter, and the United States wanted the same access in China for its chemicals manufacturers as Chinese companies already enjoyed on the U.S. market.

He urged Brazil to sign up to the existing information technology agreement, which eliminates tariffs on some high-tech products and which many developing countries take part in.

Recent tariff increases by Brazil were a "stick in the eye" for its trading partners and made the Doha talks harder, while India was sending mixed signals, he said.

Punke said the United States accepted it would have to make further concessions in negotiations but the central question was whether the emerging economies were ready to do more.

"If they're prepared to accept that responsibility we'll have a successful outcome," he said. "If they're not prepared to accept that responsibility, we won't." (Editing by Stephanie Nebehay and Jason Neely)