BERLIN (Reuters) - Iran has offered North Korea oil and natural gas as payment for help in developing nuclear missiles, German weekly magazine Der Spiegel reported on Saturday, citing unidentified Western intelligence sources.

A senior Iranian official traveled to the North Korean capital Pyongyang during the second week of October to make the offer, the magazine quoted the sources as saying. It was unclear what North Korea"s response was, it added.

Diplomats and intelligence sources say Iran is pushing ahead with plans to enrich uranium in defiance of international pressure to stop developing sensitive nuclear technology to calm fears it is seeking nuclear weapons.

Iran insists its nuclear ambitions are entirely peaceful.

Iran"s Shahab-3 missiles are based on North Korea"s Nodong rockets and Pyongyang is Tehran"s most important partner in developing missile technology, Der Spiegel said.