Bulgaria may send prosecutors to Britain to investigate the 1978 killing of a Bulgarian exile stabbed to death with a poisoned umbrella, the Foreign Office said Friday. Britain has blamed Bulgaria for the death of Georgi Markov, who fled to London in 1969 and worked for the Bulgarian service of the British Broadcasting Corp. He was killed by a poison pellet injected by an umbrella tip as he walked across London's Waterloo Bridge in September 1978. British officials suspect the murder was the work of agents of Bulgaria's Communist government, which was controlled by hard-liners until last year's reforms swept much of Eastern Europe. Britain has pressed the Bulgarian government to take responsibility. A Foreign Office spokesman said Bulgarian Ambassador Dimitar Zhulev told British officials Friday that Bulgaria was willing to send prosecutors to discuss the case with British officials. No date was given for a visit, and there were no further details.