DAMASCUS (Reuters) - Iran’s foreign minister said on Thursday U.S. participation in nuclear talks was “positive”, but France said big powers still wanted Tehran to make specific proposals to resolve a dispute over Iran’s nuclear work.

The United States said on Wednesday it was sending an envoy to Geneva to join nuclear talks with Iran for the first time, to underline to the Islamic Republic and others that Washington wanted a diplomatic solution to the impasse.

“The American participation is positive,” Iranian Foreign Minister Manouchehr Mottaki told a news conference in Damascus. “We look forward to constructive engagement”, he said, referring to a new round of talks in Geneva on Saturday.

Senior U.S. diplomat Williams Burns will join EU foreign policy chief Javier Solana and officials from Britain, France, Germany, Russia and China for the talks.

The powers are seeking a more detailed Iranian response to their enhanced offer of financial and diplomatic incentives to halt its secretive nuclear activity that could yield atom bombs.

French Foreign Minister Bernard Kouchner said the U.S. presence would be “an additional asset” and that Iran’s readiness for more talks was encouraging, despite its initially dismissive response to the revised package.

“We are waiting for an opening,” he told reporters in English outside a European security meeting in Vienna.

“I talked to (Iranian Foreign Minister Manouchehr) Mottaki and he was open, but open to what? That is always the case. We talk and talk with the Iranians, but it’s always disillusion.”

He said Tehran was still not addressing “the core of the subject” -- an enrichment suspension, or an interim freeze on steps to expand the proliferation-prone activity, to get preliminary negotiations going.

“Iran’s (written) response to our offer said, ‘OK to dialogue’, but nothing about enrichment, as if they had not read our letter,” Kouchner said.

“I have lots of hope for these talks, but I don’t expect anything from them. France has had lots of talks with Iran (on nuclear issues) but they have never produced anything.”

BEIJING WELCOMES U.S. PRESENCE

Iran says its nuclear work is for peaceful power generation, not nuclear bombs as Western leaders suspect, and it has rejected demands it give up uranium enrichment.

French Foreign Minister Bernard Kouchner gestures during a news conference in Vienna July 17, 2008. REUTERS/Herwig Prammer

Asked if she expected a positive response from Iran, U.S. Secretary of State Condoleezza Rice said: “I don’t know.”

“The point we are making is that the United States is firmly behind this diplomacy and firmly behind and unified with our allies. Hopefully the Iranians will take that message,” she told reporters.

Washington has had no relations with Iran since 1980 and would have the most to offer it in terms of relief from international political and economic sanctions, making U.S. engagement crucial to resolving the standoff, analysts say.

A British newspaper said on Thursday the United States would announce in the next month that it plans to establish a U.S. interest section in Tehran for the first time in 30 years.

“The move will see U.S. diplomats stationed in the country,” said the Guardian, describing the development as “a remarkable turnaround in policy by President George Bush who has pursued a hawkish approach to Iran throughout his time in office.”

Tensions with Iran have intensified, particularly since Tehran tested missiles last week, pushing up oil prices, rattling Israeli nerves and prompting Washington to say it would defend its allies against any possible attacks.

The Bush administration said it was not changing its stance that it will join full-blown negotiations with Iran only if Tehran first shelves enrichment activity.