LONDON, July 27: British police, chasing the bombers who tried to attack London’s transport system last week, arrested a key suspect on Wednesday in what was hailed as a major breakthrough in Britain’s biggest ever manhunt. The man, Yasin Hassan Omar, was one of four men detained in dawn raids in the central English city of Birmingham. He was taken to a top security police station in London.

The three other men were detained at another place in the Birmingham area and were taken to a local police station. Police who swooped on the house in Birmingham’s Hay Mills used a stun gun on the man, temporarily disabling him with an electric shock, and discovered a suspect package.

Omar, 24, is wanted over an attempted attack on Warren Street underground station — one of four failed bombings on July 21. He came to Britain from Somalia as a child refugee. Although police declined to identify the man taken to London, a police source told Reuters: “The arrest is much more significant than the other three.”

Prime Minister Tony Blair said: “It is an important development ... Obviously we are greatly heartened by the operations today.”