An Iranian opposition group currently in exile has stated that a delegation of North Korean nuclear warheads and ballistic missiles experts visited a military site in Tehran last April. The meetings between the two nations happened while talks between world powers were conducted regarding Iran's nuclear program.

The dissident National Council of Resistance of Iran (NCRI) is known for exposing Iran's uranium enrichment plant at Natanz and a heavy water facility in Arak back in 2002, but analysts have said that the NCRI has a clear political agenda and a mixed track record, according to The Jerusalem Post.

Iran, however, has remained steadfast, stating that allegations of nuclear bomb research being conducted in the country are baseless and are forged by its enemies.

The Paris-based NCRI said that a 7-person North Korean Defense Ministry team paid a visit to Iran during the last week of April. The group further claims that the information came from sources inside Iran, as well as within Iran's Revolutionary Guards Corps, according to Reuters.

"The delegates included nuclear experts, nuclear warhead experts and experts in various elements of ballistic missiles including guidance systems," the group said.

The NCRI further states that the North Korean delegation was taken to the Imam Khomenei complex in secret. The site is controlled by the Defense Ministry of Iran.

A panel of experts from the United Nations, tasked with monitoring North Korea's compliance with its sanctions, previously found out that Pyongyang and Tehran have been regularly exchanging ballistic missile technology, in clear violation of U.N.-imposed sanctions, according to Reuters.

NCRI spokesman Shahin Gobadi said that Iran has been unwavering in its development of nuclear weapons.

"Tehran has shown no interest in giving up its drive to nuclear weapons. The weaponization program is continuing and they have not slowed down the process," he said.