Iranian President Hassan Rouhani said on Sunday he hoped British Prime Minister Boris Johnson's "familiarity" with the Islamic Republic will help improve relations between Iran and Britain.

In a message posted on the official Iranian presidency website, Rouhani congratulated Johnson on his appointment.

Tensions between London and Tehran took a turn for the worse this month. Iranian commandos seized a British-flagged tanker in the Strait of Hormuz on July 19, two weeks British forces captured an Iranian oil tanker near Gibraltar, accusing it of violating sanctions on Syria.

"I hope that your familiarity with the issues of the relations of Iran and England and your presence once in Tehran will be a considerable help to get rid of existing obstacles in the growth and expansion of relations between us," Rouhani said in the statement.