"Was told by FM Zarif that Iran wants to resolve the issue and is not seeking to escalate. Also spoke to @FabianPicardo who is doing an excellent job coordinating issue and shares UK perspective on the way forward," he added.
Iran has previously denied that the tanker, which was seized by Gibraltar officials and Britain's Royal Marines on July 4, was bound for Syria. It was suspected of breaking EU sanctions.
UK raised the level of threat to British shipping in Iranian waters to 'critical' on July 9. The country also claimed that Iran failed to halt a British oil tanker in the region -- an accusation which has since been dismissed by Tehran.