Ukraine is investigating what became of its cold war nuclear arsenal in response to revelations that at least 18 unloaded cruise missiles were smuggled to Iran and China in 2001.

Petro Poroshenko, secretary of Ukraine's National Security Council, said he had ordered the Defence Ministry and SBU secret police to make a full account of the arsenal, which was supposed to have been destroyed or transferred to Russia after the break-up of the Soviet Union.