LONDON - British police hunting London bombers have admitted killing a Brazilian electrician by mistake - a blunder that dealt a blow to their efforts to track down militants they fear could strike again.
In another dramatic twist to the massive manhunt, police believe they may have established links between the teams of bombers who struck London twice.
Police hunting four men who tried to bomb London's transport system chased and shot dead a man on Friday who had been under surveillance and refused orders to halt.
Thursday's attempted attacks came two weeks after four suicide bombers killed 52 commuters in similar attacks.
Police expressed regret for the tragedy and named the innocent victim as Jean Charles de Menezes, a 27-year-old electrician who had been living in London for three years.
Brazilian Foreign Minister Celso Amorim is demanding clarification from Britain about the shooting.
The victim's cousin, Lady Menezes, said: "It's an injustice, something needs to be done."
Both security experts and Muslim leaders are fearful of a backlash after the bombings accused police of adopting "shoot-to-kill" tactics."
Anti-terrorism expert Robert Ayers of the Royal Institute of International Affairs said police have "demonstrated that they are operating on the premise right now that if they suspect that someone is a bomber, and that the public is going to be endangered by him, they have shoot-to-kill orders."
"Simple nervous system shut-down, that is the objective," Ayers said.
"To give license to people to shoot to kill just like that, on the basis of suspicion, is very frightening," Azzam Tamimi of the Muslim Association of Britain said.
In one of the biggest police probes in British criminal history, security sources indicated there could be links between the two London attacks.
The sources, cited by British media, said two of the July 7 bombers attended a whitewater rafting trip at the same centre in Wales as some of the July 21 bombers.
This was based on evidence discovered in rucksacks left behind by the failed bombers. Detectives believe the trip could have been used as a bonding exercise.
The Abu Hafs al Masri Brigade, an al Qaeda-linked group, has claimed responsibility for Thursday's bombing attempts and those of July 7, but the group's claims of responsibility for previous attacks in Europe have been discredited by security experts.
London's Mayor Ken Livingstone argued that terrorism was an international scourge that could strike anywhere and he was dismissive of the decision by Italian soccer club Inter Milan to cancel a pre-season tour of England.
"I think that it is a very silly thing to do because it is playing the terrorists' game. They want to change the way we live. The terrorists, I am sure, will be celebrating their decision.
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