Talks on the Iranian nuclear issue resumed here Monday, as Iran declared itself to be self-sufficient in nuclear fuel supply and voiced harsh criticism of attempts to assassinate its nuclear scientists.

The two days' closed-door meeting is being attended by Iran's chief nuclear negotiator Saeed Jalili, and European Union (EU) foreign affairs chief Catherine Ashton on behalf of the five UN Security Council permanent members plus Germany (G5+1).

Representatives braving chilly rain arrived at the Geneva International Conference Center, and the meeting was delayed for one hour.

It is the first such talks in 14 months since the last session in October 2009 ended without any substantial agreement.

Iran has entered the talks with a tough stance. Speaking to state TV channel IRINN on Sunday, Ali-Akbar Salehi, head of Iran's atomic energy authority, said the first Iranian-made uranium yellowcake, using domestically mined uranium ore, was shipped to the central city of Isfahan for processing.

The progress would make the UN embargo on nuclear raw materials futile.

Iranian officials have also accused the West and Israel of plotting assassinations against two Iranian nuclear scientists. In two separate incidents in northern Tehran last week, Iranian nuclear scientist Majid Shahriari was killed and Fereidoon Abbasi was wounded when they were driving to work.

Iran has reiterated that it would not negotiate over its inalienable rights of nuclear enrichment at the upcoming talks with the six powers.

The West has long accused Iran of secretly developing nuclear weapons under civilian disguise, although Tehran has always denied such charges.