LONDON — In a significant indication of warming Western relations with Iran after a deal limiting its nuclear program, Foreign Secretary Philip Hammond will reopen Britain’s embassy in Tehran, probably on Sunday, British officials said Thursday.

Four years ago, in November 2011, the ambassador’s residence there was ransacked and the British flag burned by protesters angry about the economic sanctions imposed on Iran in response to its nuclear program and its flouting of United Nations Security Council resolutions.

Mr. Hammond is expected to travel to Iran this weekend with a small delegation of businesspeople, including representatives from Royal Dutch Shell, a British official said, speaking anonymously in accordance with diplomatic practice.