The man whom Western intelligence agencies say may very well be the head of Iran’s clandestine nuclear weapons program was present as an observer last week when North Korea carried out a critical nuclear test, The British Sunday Times reported.

According to the report Sunday, Mohsen Fakhrizadeh-Mahabadi very rarely leaves Iranian soil due to fear that Israel’s Mossad will make an attempt on his life, following an alleged pattern of previous assassinations of Iranian nuclear scientists.

Fakhrizadeh-Mahabadi is currently pursuing technology that would enable his country to assemble a nuclear warhead compact enough to be fitted to the ballistic missile technology in its possession, Western intelligence sources reportedly said.

North Korea’s test last week, during which it detonated a nuclear device at a remote underground site, was a key step en route to just such a prototype, South Korean defense officials and Japanese government sources were quoted as saying.

“The atomic bomb appears to have been made compact enough to be placed on a missile,” a Japanese source reportedly said.

The test was roundly condemned the world over — even Iran issued an ostensible scolding – with US President Barack Obama calling it a “highly provocative act” that threatened security and international peace.

Meanwhile, North Korea’s official state media said the test was aimed at coping with “outrageous” US hostility that “violently” undermined the North’s peaceful, sovereign right to launch satellites. 

Evidence of military cooperation between Iran and North Korea has been compounded by satellite images showing distinct similarities between an Iranian missile launch pad and a North Korean missile facility, the report said.

Iran’s Shahab-3 long-range missile is based on the North Korean Nodong-1 and is estimated to have a range of up to 2,000 kilometers. In December, Iranian agents were reportedly on hand in North Korea for a long-range missile test.

Fakhrizadeh-Mahabadi, the Iranian nuclear official, reportedly may have traveled to Pyongyang through China, an ally of North Korea that has also allegedly provided nuclear and military assistance to Tehran.

Iran, like North Korea, is under stiff sanctions, and negotiations with the West over its nuclear program have similarly stalled.

Iran maintains the program is peaceful, for generating energy and for medical research, not for weapons.

According to Western assessments, the capacity to assemble a nuclear warhead that can be delivered via Shahab missile technology is one of the last remaining obstacles to an Iranian nuclear strike capability.

Experts say Iran already has enough enriched uranium for several weapons if it is further enriched. Last week, Tehran showed off new-generation centrifuges that can enrich uranium four to five times faster than its present working model.

The Associated Press contributed to this report.