TEHRAN (Dispatches) - Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei has condemned the US and Israeli spy agencies, CIA and Mossad, for the recent assassination of an Iranian nuclear scientist.

“This cowardly [act of] terror, whose perpetrators and plotters will never dare to confess to their dirty and hideous crime or accept responsibility for it, has been carried out by the planning or support of CIA and Mossad [spy] services, like all other crimes of the network of international state terrorism,” said Ayatollah Khamenei late on Thursday in a message of condolence on the death of Mostafa Ahmadi Roshan.

The assassination attempt shows that “the global arrogance spearheaded by the US and Zionism has reached a deadlock in confrontation with the determined, devout, and progressive nation of Islamic Iran,” the leader added.

Ayatollah Khamenei went on to say that Iran's rapid scientific progress is not dependent on individuals but is a “historic movement” and arises from the “invulnerable national resolve” of Iranians.

Insisting that the Iranian nation will continue on its path with determination, the leader pointed out that Iranians will not overlook the crime and never stop efforts to bring the perpetrators and those behind the assassination to justice.

Meanwhile, President Mahmoud Ahmadinejad also condemned the assassination of an Iranian nuclear scientist, describing it as an act of vengeance by hegemonic powers who failed to impede the country's progress.

The assassination of Iranian scientists is indicative of the failure of selfish global powers, which are well aware of their defeats against Iran's scientific, political and economic breakthroughs, and therefore have resorted to avenge their frustrations against the Iranian nation, President Ahmadinejad said in a message extending his condolences on Friday over the assassination of Iranian nuclear scientist.

He condemned the “hegemonic powers” and “global Zionism” for the “hostile” and “inhumane” assassination and said these powers were wrong to presume that they could hinder Iran's progress by means of such attacks.

Not only such measures will fail to halt Iran's advancements on the path of development, but they will also strengthen the Iranians' resolve in making more scientific breakthroughs, the Iranian chief executive stated.

The president also offered his condolences to the family of Ahmadi Roshan whose assassination prompted a wave of condemnation.

In the same context, the secretary of Iran's Supreme National Security Council says the assassination of Iranian nuclear scientist Mostafa Ahmadi Roshan bears the hallmarks of a US-Israeli hit.

“US Secretary of State Hillary Clinton must answer this fundamental question for the public opinion. How come the terrorists only target those whose names have been mentioned on the list of US sanctions regime or those in UN Security Council's resolution?” Saeed jalili said.

Speaking to Press TV during a special ceremony in which university students, lecturers and officials paid their final respects to the assassinated nuclear scientist, Jalili also criticized the International Atomic Energy Agency (IAEA) for apparently leaking confidential information on Iran's nuclear experts to Western intelligence agencies.

Mostafa Ahmadi Roshan was deputy of commercial affairs at Iran's Natanz nuclear installations, which are under constant supervision of the IAEA, said Jalili, adding that “How come despite such transparent cooperation [on the part of] Iran, [the country] is still under constant threats, pressures and sanctions?”

Jalili expressed confidence that those who take radical measures to challenge Iran's nuclear rights are laying bare their frustrations, defeats and breaking points.

“These terrorist attacks reveal that Iran's enemies couldn't achieve their objectives through military, diplomatic or economic pressures,” he noted.

On January 11, an unknown motorcyclist attached a magnetic bomb to the scientist's car near a college building of Allameh Tabatabaei University in Tehran. Ahmadi Roshan was immediately killed and his driver, who had sustained injuries, died a few hours later in hospital.

Ahmadi Roshan, a Sharif University of Technology chemical engineering graduate and the deputy director of marketing at iran's Natanz nuclear facility, was killed immediately and his driver, who had sustained injures, passed away a few hours later in hospital.

The latest terrorist attack comes as Iran has reached an agreement with the P5+1 -- Britain, China, France, Russia, and the United States plus Germany -- to hold negotiations in Turkey.

The US, Israel and their allies accuse Iran of pursuing a military nuclear program and have used this allegation as a pretext to sway the UNSC to impose four rounds of sanctions on Iran.

Based on these accusations, they have also repeatedly threatened Tehran with the "option" of a military strike.

This is while in November 2011, some of the US presidential hopefuls called for conducting covert operations ranging from assassinating Iranian nuclear scientists to launching a military strike on Iran as well as sabotaging Tehran's nuclear program.

The calls for assassinations are not idle threats as a number of Iranian scientists have been assassinated over the past few years. Professor Majid Shahriari and Professor Masoud Ali-Mohammadi are among the victims of these acts of terror.

On November 29, 2010, Shahriari and Fereydoun Abbasi were targeted by terrorist attacks; Shahriari was killed immediately and Dr. Abbasi, the current director of iran's Atomic Energy Organization, only sustained injuries.

Iran says as the UN Resolution 1747, adopted against Tehran in March 2007, cited Abbasi's name as a "nuclear scientist," the perpetrators were in a position to trace their victim.

According to reports, Ahmadi Roshan had recently met International Atomic Energy Agency (IAEA) inspectors, a fact which indicates that the IAEA has leaked information about iran's nuclear facilities and scientists.

Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei