Mossad, Israel's elite secret service agency, has been training assassins to kill Iranian nuclear scientists, a new report from NBC News claimed.

United States officials told NBC that Israel has been funding, arming and training members of the People's Mujahedin of Iran (MEK), a dissident group in Iran that is officially listed as a terrorist organization in the U.S.

If true, the report confirms allegations made by Iranian leaders, who have blamed Israel for the recent deaths of a number of nuclear scientists.

In January, Mostafa Ahmadi Roshan, a chemistry professor and a director at the Natanz uranium enrichment facility near Isfahan in central Iran, was assassinated in Tehran by two unidentified men on a motorcycle, who planted a bomb on his car.

The bomb was a magnetic one and the same as the ones previously used for the assassination of the scientists, and is the work of the Zionists, Deputy Tehran Governor Safarali Baratloo stated after the incident.

Baratloo was refering to the deaths of Tehran University professor Masoud Ali-Mohammadi, who was killed in a motorcycle explosion in January 2010, and nuclear scientists Majid Shahriari and Fereydoun Abbasi, who were killed by car bombs in November 2010.

This terrorist act was carried out by agents of the Zionist regime and by those who claim to be combating terrorism (the U.S.) with the aim of stopping our scientists from serving, Ahmadi Roshan, Natanz nuclear facility deputy director, told state television about  Roshan's murder.

They [Israel and the U.S.] should know that Iranian scientists are more determined than ever in striding towards Iran's progress.

The United States continues to deny its involvement in killing Iranian scientists, but Israel has remained mum on the issue.

Additionally, the U.S. officials told NBC that President Obama knew that Israel was behind the assassinations, but chose not to get involved.

The MEK, which is vehemently antagonistic towards the current Iranian government, has been accused of killing U.S. contractors in the 1970s and has been connected to the American Embassy takeover in Tehran in 1980.

French daily newspaper Le Figaro also claimed earlier that Mossad had been recruiting Iranian Kurds to subvert Tehran's nuclear program.