The White House said on Saturday that President Donald Trump and British Prime Minister Theresa May discussed over phone Friday on issues concerning Iran and the Democratic People's Republic of Korea (DPRK).

The two leaders discussed cooperation between Washington and London to advance shared national security interests, including efforts to enforce sanctions on Syria and to ensure that Iran does not obtain a nuclear weapon, the White House said in a statement.

They also discussed efforts to achieve the final, fully verified denuclearization of the DPRK.

British Royal Marines on Thursday helped the authorities in Gibraltar seize an Iranian oil tanker "Grace 1", which reportedly was heading to Syria "in breach of EU sanctions."

Spain's acting foreign minister said the seizure of the "Grace 1" was at the US request.

Iran called the seizure of Iranian oil tanker as "illegal." Iranian Foreign Ministry on Thursday summoned British ambassador to Iran following the seizure.