WASHINGTON - Signaling again its eagerness for talks with Iran, the Obama administration said yesterday that it will for the first time become a regular participant in group negotiations aimed at ending Iran's suspected nuclear-weapons ambitions.

In contrast with the Bush administration, which joined in the sessions only once, the Obama administration will participate with other world powers "from now on," said Robert Wood, the chief State Department spokesman.

He did not rule out one-on-one discussions with Tehran, saying, "It's a little early to talk about that right now."

The meetings include the five members of the United Nations Security Council - China, Russia, Britain, France, the United States - as well as Germany.

The Bush administration, which generally sought to isolate Iran, sent the State Department's No. 3 official, William Burns, to the meetings only once, last July, and then only as an observer.

The diplomatic group is proposing a new meeting with Iran. Wood said the administration would send Burns if Tehran agreed as a full participant.

The approach is in a series of overtures from the new administration.

President Obama last month offered a new start to relations with Iran, saying he wanted to end the enmity that began 30 years ago when an Islamic revolution toppled the shah of Iran and Iranian radicals held U.S. diplomats hostage for well over a year.

The United States and Iran have not had diplomatic relations since the 1979 revolution.

A Swiss newspaper reported yesterday, however, that for six years groups of American and Iranian academics and others have been secretly traveling to Geneva and other European cities for closed-door brainstorming sessions on how to break through decades of hostility.

According to a detailed report in the French-language Le Temps, the informal meetings have taken place with the full knowledge of officials in Washington and Tehran.

About 400 people have taken part in the discussions - called the "Track II" process - including experts and scholars from Europe, the Arab world and Israel.

None of the participants would speak on the record about the meetings. But Switzerland's foreign minister, Micheline Calmy-Rey, told reporters her government was fully aware of the contacts, the last of which took place from March 6 to March 8.

Ellen Laipson, president of the Stimson Center, a Washington think tank, said yesterday's move on directly joining nuclear talks with Iran was a "small, incremental step," but part of an effort to "send a fairly consistent message that we really mean it - we really want to do business."

She said that while Tehran has had a "slightly cranky response" to most of the U.S. overtures, the Iranians also "haven't said that the offers were totally unacceptable."

President Mahmoud Ahmadinejad said yesterday that his country would welcome talking to the United States "if it is based on honesty."

Karim Sadjadpour, an Iran specialist at the Carnegie Endowment for International Peace, said while the Obama administration has been moving rapidly to try to engage Iran, the Iranian government has not come close to a consensus and will need more time to debate the U.S. offer.

The diplomatic group, called the P-5 plus one, made a broad offer of political and economic incentives to the Iranians last year, but was rebuffed. If the seven nations do resume talks, they would consist of preliminary discussions about whether to resume in-depth negotiations.

The difficulty in easing tensions between Tehran and Washington was made apparent yesterday when Iranian authorities said a detained American journalist would be tried for espionage.

The administration has been pressing for Roxana Saberi's release since she was detained two months ago.

Secretary of State Hillary Rodham Clinton said U.S. officials were "deeply concerned" by word that she would face trial next week. "We wish for her speedy release and return to her family," Clinton said.

This article includes information from the Associated Press.