이란 당국이 11일 테헤란에서 발생한 폭탄 테러로 핵 과학자가 숨진 사건을 조사하기 위해 사고 차량을 옮기고 있다. / AP=연합뉴스

"What is seen in espionage films as a simple operation is a result of hard work, many months of intelligence gathering and a well trained team," an unnamed Israeli source said.

The source was describing the assassination of Iranian nuclear scientist and Natanz official Mostafa Ahmadi Roshan in Tehran.

According to the London-based UK Sunday Times, Mossad agents are responsible for the targeted attack which killed the Iranian scientist last week. "There is zero tolerance for mistakes. By nature, every failure not only risks the neck of the agents but also risks turning into an international scandal," the source told the newspaper.

It was a classic assassination mission for Israel, it claimed. According to the newspaper, Israeli Mossad agents gathered in small groups to observe key locations across Tehran. The agents monitored Roshan's every move from an improvised control room in a safe house nearby.

Meanwhile, the Iranian intelligence headquarters in the city center was also under observation, less than a mile away from the assassination location.

Suddenly, they noticed a number of cars and people running. The streets quickly filled with police officers. One of the agents, listening to the radio communication between Tehran police and security forces confirmed the irregular activity.

Later that day, the paper claimed, Roshan's bodyguard and driver checked the state-issued silver Peugeot 405, for explosives. He then proceeded to slip into the driver's seat and waited for the scientist.

Just before 8 a.m., an Israeli observer reported the objective had left via an intercepted message. Then the assassins' commander made the final decision, telling agents who were standing by with a motorcycle in a hidden garage to "go."

At around 8:20 a.m., the agents tracked down the scientist's car, the Sunday Times reported. The masked man made sure the passenger was in fact Roshan before proceeding to attach a magnetic bomb to the vehicle, intended primarily to injure Roshan. Nine seconds later an explosion was heard. The scientist was killed instantly. The driver was badly injured and died in the hospital later that day.

New information also reveals that killed nuclear scientist also had a hand in developing Iran's missile program, claimed Roshan's commander from Basij, a volunteer organization under the Iranian Revolutionary Guards.

According to him, Roshan initially worked for the defense ministry and after sometime was "responsible for other sensitive things" at the Atomic Energy Organization of Iran (AEOI). Roshan studied chemistry at Sharif University of Technology in Tehran, which has been previously linked to the development of arms and missiles, with the help of the Iranian Revolutionary Guard.

According to the Israeli source, targeting nuclear scientists is a precursor to a military strike and not an alternative, in an ongoing attempt to stop Iran's nuclear program.