A new round of international talks aimed at finding a solution to the Iranian nuclear issue began Thursday on the outskirts of Geneva.

The talks between EU foreign policy chief Javier Solana and Iran's chief nuclear negotiator Saeed Jalili are also attended by senior diplomats from the group of six countries negotiating with Iran about its nuclear program -- the United States, Britain, France, Russia, China and Germany.

This is the first high-level meeting between Iran and the six countries since a session in July 2008 ended without substantive progress. It's also the first time that the United States formally joins in talks with Iran -- the United States was present at the 2008 talks only as an observer.

The United States and other Western powers have long accused Iran of engaging in nuclear weapon programs, but Tehran insists its nuclear efforts are for civilian purposes.

Ahead of the talks, U.S. officials stressed that Iran must allow unfettered inspections over its nuclear facilities, especially a newly disclosed uranium enrichment plant.

Solana proposed "freeze for freeze" -- Tehran must freeze its uranium enrichment program at current levels in exchange for no further UN sanctions.

But Tehran has said that it would not discuss anything concerning its nuclear rights, but is open to discussions on disarmament, non-proliferation and other general security issues.

Thursday's talks are expected to last a full day, a senior U.S. official said on Wednesday. He did not rule out the possibility of informal bilateral contacts between U.S. and Iranian officials.

"Like our partners, we're committed to meaningful negotiations to resolve what are growing international concerns about Iran's nuclear program," the official said on condition of anonymity.

He said the first task of the Geneva talks "is to establish whether the Iranians are ready to engage on the nuclear issue."

Another urgent task is to ensure the free access of the International Atomic Energy Agency (IAEA) to the "clandestine facility" located near the Shi'ite holy city of Qom, as well as to people and documents connected with that facility, he added.