GENEVA

Israel's intelligence agency, the Mossad, was likely behind bombings and phone threats on German and Swiss companies linked to a covert Pakistani nuclear program, a Swiss historian told a Swiss daily, without citing a proof.

The claims were carried in a report in a Swiss German-language daily, Neue Zurcher Zeitung (NZZ), which said that in the 1980s, Pakistan worked with Iran to produce nuclear weapons materials.

The Mossad's participation in the bombings was probable, but there is no "smoking gun" to prove involvement, Adrian Hanni, a historian and intelligence service expert, told the daily.

The administration of then-US President Jimmy Carter sent a diplomatic warning to Swiss and German companies that they are said to have provided technical support to Pakistan's nuclear program in 1981.

Within a few months of the US warning, three facilities linked to the European companies were bombed.

There was an explosion in the house of an employee of the German company Cora Engineering in the Swiss town of Chur on Feb. 20, 1981.

There was another blast at a Walischmiller company factory in Markdorf, Germany on May 18, 1981, and another at the Heinz Mebus engineering office on Nov. 6th, 1981, the report said.

Mebus was in talks with Pakistani engineer Abdul Kadir Han, known as the owner of the nuclear project, in Zurich, Switzerland.

Threatening phone messages were sent to other commercial organizations, added the report.

"The suspicion that the Mossad might be behind the attacks and threats soon arose," the daily noted.

"For Israel, the prospect that Pakistan, for the first time, could become an Islamic state with an atomic bomb posed an existential threat."

A previously unknown entity that claimed responsibility for the explosions, the Organization for the Non-Proliferation of Nuclear Weapons in South Asia, was "never heard from" again following the incident, according to the NZZ.