London: British Foreign Secretary Philip Hammond will join the Iran nuclear talks in Switzerland this weekend, a foreign ministry spokesman said on Friday.
Hammond, who is on a visit to the United States, earlier this week said an agreement was "deliverable" but urged Iran to make "tough decisions".
A spokesman for French Foreign Minister Laurent Fabius, who has warned against a soft deal leaving Iran with the possibility of obtaining nuclear weapons, has said he will join the talks on Saturday.
Fabius and Hammond will join US Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif in Lausanne.
After 18 months of intense negotiations, the fresh round of talks is aimed at reaching a deal before the final deadline of March 31.
Six world powers negotiating with Iran since late 2013 want Tehran to disable parts of its nuclear infrastructure to put an atomic bomb out of reach and end a 12-year standoff.
Iran insists its nuclear programme is for civilian purposes.