REPORTING FROM TEHRAN AND BEIRUT — Britain is promising “serious consequences” after hundreds of demonstrators stormed its embassy and another diplomatic compound in Tehran on Tuesday, chanting “Death to Britain” and setting fire to the British, U.S. and Israeli flags.
“We hold the Iranian government responsible for its failure to take adequate measures to protect our embassy, as it is required to do,” British Foreign Secretary William Hague said in a statement.
He said he had spoken with the Iranian foreign minister to “protest in the strongest terms about these events and to demand immediate steps to ensure the safety of our staff and of both embassy compounds.”
The Iranian charge d’affaires in London was also summoned to the Foreign Office and Prime Minister David Cameron chaired a meeting of an emergency Cabinet group to discuss the incidents, he said.
“Clearly, there will be other, further and serious consequences,” Hague said.
Iran’s Foreign Ministry issued a statement expressing regret for “some of the unacceptable behaviors” by demonstrators and said it had requested an immediate investigation.
Some of the protesters climbed over the gates and into the embassy compound in downtown Tehran, where they tossed gasoline bombs and hoisted the Iranian flag in place of the British banner.
A separate group forced its way into another British diplomatic compound in the north of the city, where the demonstrators seized documents and staged a sit-in, according to a report by the quasi-official Fars news agency.
Fars said police had secured the release of six embassy employees “taken hostage” by protesters at disputed gardens in the compound, which is used by embassy staff and other officials. But the official Islamic Republic News Agency said the protesters had been protecting the employees.
Hague said that it appeared all embassy staff and their dependents were accounted for but that officials were “urgently establishing the whereabouts of our locally engaged security staff.”
He warned British nationals against all but essential travel to Iran and advised the small number in Iran to stay indoors and to await further advice.
The demonstrators were angry about British support for stepped-up Western sanctions after the International Atomic Energy Agency released a report saying Iran may be secretly working to develop a nuclear weapon.
Chancellor of the Exchequer George Osborne announced last week that Britain was severing financial ties with Iranian banks, which British officials accuse of facilitating Tehran's nuclear program. Iran says the program is only for civilian purposes.
Iran's Guardian Council, which vets legislation from parliament, approved a bill Monday calling for a downgrading of diplomatic relations with Britain and the expulsion of its ambassador, Dominick Chilcott.
Britain called the move "regrettable" and promised to "respond robustly" if Iran acts on the legislation.
— Ramin Mostaghim in Tehran and Alexandra Zavis in Beirut. Henry Chu and Janet Stobart in London contributed reporting.
Video: On Tuesday, dozens of hard-line Iranian demonstrators stormed the British Embassy in Tehran, bringing down the Union Jack flag and throwing documents from windows. Credit: Associated Press