World

Britain's foreign minister says UK must tread carefully in relationship with Iran

  • Iran's President Hassan Rouhani, right, welcomes British Foreign Secretary Philip Hammond at the start of their meeting in his office, in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)

    Iran's President Hassan Rouhani, right, welcomes British Foreign Secretary Philip Hammond at the start of their meeting in his office, in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)  (The Associated Press)

  • British Foreign Secretary Philip Hammond sits in a meeting with Iran's President Hassan Rouhani at the presidency office in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)

    British Foreign Secretary Philip Hammond sits in a meeting with Iran's President Hassan Rouhani at the presidency office in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)  (The Associated Press)

  • Iran's President Hassan Rouhani sits in a meeting with British Foreign Secretary Philip Hammond at the presidency office in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)

    Iran's President Hassan Rouhani sits in a meeting with British Foreign Secretary Philip Hammond at the presidency office in Tehran, Iran, Monday, Aug. 24, 2015, a day after Hammond attended the reopening of Britain's embassy in the capital. The reopening takes place in the wake of a landmark nuclear deal between Iran and world powers. The embassy has been closed since November 2011, when it was stormed by demonstrators protesting the imposition of international sanctions against the Islamic Republic. (AP Photo/Ebrahim Noroozi)  (The Associated Press)

Britain's foreign minister says Iran is a major regional player that can be an ally in fighting terrorism — but the U.K. must "tread carefully" in its relationship with Tehran.

Tehran and world powers struck a deal last month on Iran's contested nuclear program, and on Sunday Britain and Iran reopened their respective embassies after a break of several years.

Foreign Secretary Philip Hammond, who met Iranian President Hassan Rouhani in Tehran Monday, said the two countries shared common ground despite a "deep legacy of distrust."

He said they agreed on the need to defeat the Islamic State group, and to stop opium from Afghanistan reaching Europe.

Hammond told the BBC that "Iran is too large a player, too important a player in this region, to simply leave in isolation."