Iranian scientists witnessed North Korea's latest nuclear test last Tuesday, a western diplomatic source has told Japan's Kyodo News.

Kyodo on Friday reported that Tehran asked in November for Iranian scientists to be allowed to witness the nuclear test and offered to pay tens of millions of U.S. dollars.

According to the source, the suggestion came from Iran's vice president and chief of the country's nuclear agency in a national security meeting with Iranian President Mahmoud Ahmadinejad and senior ministers on Nov. 22 last year. Ahmadinejad authorized that the payment be made through Bank of Kunlun in Beijing.

Kyodo said it is unclear whether the Iranian scientists actually witnessed the test.

The unnamed source was quoted as saying the proposal casts further doubt on Iran's claims that its nuclear program is peaceful. He added it would be "very worrying" if Iran got nuclear test knowhow from North Korea.

Kyodo sa id Iranian defense ministry officials have been in North Korea since October last year as part of bilateral cooperation in missile and nuclear arms development. They are apparently housed in a military facility 85 km from the border with China.

North Korea has sold missiles to Iran in the past as the two international pariahs boost military ties.