Iran has again accused Israel and the United States of killing one of its top scientists, whose funeral took place on Friday.
Iran's supreme leader, Ayatollah Ali Khamenei, called the deadly attack on 32-year-old Mostafa Ahmadi Roshan "abominable" and "cowardly." He claimed it was carried out "with the planning or support of the intelligence services of the CIA and Mossad."
Roshan, a deputy director of Iran's main uranium enrichment plant, was killed on Wednesday in Tehran when two men on a motorbike attached a magnetic bomb to his car. His driver, who was also his bodyguard, also died in the blast.
He was the fourth Iranian scientist to be killed in an explosion in the past two years.
US denial of involvement
In a letter to United Nations Secretary General Ban Ki-moon on Thursday, Iran's ambassador to the world body, Mohammad Khazaee, called on the UN to condemn the killings.
"There is firm evidence that certain foreign quarters are behind such assassinations. As has been claimed by these circles, such terrorist acts have been carried out as part of the efforts to disrupt Iran's peaceful nuclear program, under the false assumption that diplomacy alone would not be enough for that purpose," the letter said.
The United States has strongly denied having anything to do with the murder.
US Secretary of State Hillary Rodham Clinton said her country had had no role in the killing, and the US administration has condemned the attacks. Defense Minister Leon Panetta said on Thursday that US officials had "some ideas" who may be behind the killing, but insisted there was no US involvement.
Israeli officials, in contrast, have hinted at covert campaigns against Iran, without a direct admission of involvement.
However, Israeli President Shimon Peres told broadcaster CNN on Friday he was unaware of any Israeli involvement in the bombing.
The US and its allies are pressuring Iran to halt uranium enrichment amid fears that Tehran's nuclear program is aimed at producing atomic weapons. Both the US and the European Union are considering tightening economic sanctions in a bid to deter Tehran from continuing its nuclear work.
In an escalation of tensions, Iran has warned that it could close off the Strait of Hormuz - a vital oil transport route - if the sanctions are imposed.
The US has warned that such a blockade would be a "red line" that Iran should not cross and has sent two aircraft carriers to waters near the Gulf.
This comes as the UN's nuclear watchdog, the International Atomic Energy Agency, on Thursday confirmed that Iran was increasing its production of uranium enriched to 20 percent.
The uranium could theoretically be turned into weapons-grade material more quickly than lower-enriched uranium.
Author: Timothy Jones (AFP, AP)
Editor: Nancy Isenson