Iran said on Thursday it has arrested "some elements" working with Western spy agencies and connected to the murder of a senior nuclear scientist, amid claims Tehran's scientists were the targets of "terrorists."

"The three spy agencies of Mossad, CIA and MI6 had a role in the (attacks) and, with the arrest of these people, we will find new clues to arrest other elements," Intelligence Minister Heydar Moslehi was quoted as saying on state television's website.

Moslehi did not say how many people were arrested or what specifically they are accused of. He only said they were a part of a "major group" that took part in the killing and that planned to carry out "widespread missions."

On Monday, unidentified assailants attached bombs to the cars of two prominent scientists in Iran's nuclear programme.

Twin blasts killed one, Majid Shahriari, and wounded the other, Fereydoon Abbasi Davani. Three other people were also wounded.

Iran immediately blamed the attacks on the intelligence services of the United States and Israel, which suspect Tehran's nuclear ambitions harbour a military dimension. The Islamic republic denies the charge.

Iran's atomic chief, Ali Akbar Salehi, said in a report on Thursday that security for nuclear scientists would be stepped up.

"Based on a recent decision, it has been arranged that the security detail (of nuclear scientists) will be multiplied and other protection techniques will also be applied," Salehi was quoted as saying by ISNA news agency.

"Dr Shahriari was not alone as he was with his security detail," Salehi said. "But the evil methods that enemies employ are unpredictable."

"Since last year, we put under protection ... hundreds of our scientists and experts working in the nuclear field," Salehi said.

In January, another Iranian nuclear scientist, Masoud Ali Mohammadi, was killed in a bomb attack Tehran blamed on "mercenaries" in the pay of Israel and the United States.

Meanwhile, Iran's envoy to the International Atomic Energy Agency, Ali Asghar Soltanieh, charged that UN Security Council members were to blame for the attacks on scientists by publishing the names of physicists involved in Iran's nuclear programme in sanctions resolutions.

"Those experts and scientists who have been fully cooperating with (UN) inspectors, their names have immediately gone to the sanction lists of the European Union and United Nations Security Council. Now they are targeted and they are killed, one by one," Soltanieh said on the sidelines of an IAEA board meeting in Vienna.

"Those who are proponents of the resolutions of the UN Security Council and put the names of these scientists (on the lists), they are responsible for this blind assassination by terrorists," Soltanieh said.

The Security Council has called on Iran in six resolutions -- four of which impose sanctions -- to halt its controversial atomic work as part of the international community suspects Tehran is seeking nuclear weapons capability.

Soltanieh said Iran welcomed next week's meeting in Geneva with the so-called P5+1 grouping UN Security Council permanent members Britain, China, France, Russia and the United States with Germany.

"We welcome this development but we advise them to seize this opportunity to prove their political determination that they want a constructive negotiation with a conducive environment in order to settle down all the global issues in a peaceful manner with a collective cooperation," Soltanieh said.

The December 6 and 7 talks come after months of stalling by Tehran.

burs/afq/al