Thirteen Britons were killed and many other British citizens were feared to be among the thousands dead after a tsunami devastated popular tourist resorts across southern Asia, British officials said on Monday. Ten Britons were killed in Thailand, one died in Sri Lanka and two in the Maldives, the Foreign Office said, while there were reports of many others casualties across the region. Foreign Secretary Jack Straw said the number of British deaths was likely to rise. "We've had a number of reported deaths, that is deaths of British nationals reported to our embassies and high commissions, but they've not yet been confirmed," Straw told BBC radio.