Iran's deputy foreign minister says Britain will reopen its embassy in Tehran on Sunday after it being closed for nearly four years.

Majid Takht-e-Ravanchi also told state television on Saturday that the Iranian Embassy in London also will reopen at the same time.

Takht-e-Ravanchi says British Foreign Secretary Philip Hammond will attend the reopening of the British Embassy in Tehran on Sunday. It will be the first visit by a British foreign secretary to Iran since 2003.

Takht-e-Ravanchi said the two embassies will operate at charge d'affaires level.

The British Embassy has been closed since hard-liners protesting the imposition of international sanctions stormed it in November 2011.

The recent nuclear deal between Iran and world powers helped accelerate a thaw in relations between Britain and Iran.