LONDON — London's police chief said he wants to ensure Britain's anti-terror investigators are not affected by criticism over the killing of an innocent man, telling a Sunday newspaper that the most important task is to prevent further attacks.

London's police have been fiercely criticized after armed officers shot and killed Jean Charles de Menezes, a 27-year-old Brazilian who was wrongly suspected of being a suicide bomber.

Menezes was shot seven times in the head on July 22 by police who had tailed him to a subway station the day after four bombs were carried onto London's transit system but failed to detonate fully. The attacks came two weeks after four suicide bombers killed 52 commuters on the London Underground and a bus.

"We have to concentrate on how we find the people who are helping or thinking about planning further atrocities," Metropolitan Police Commissioner Sir Ian Blair was quoted as telling Sunday's News of the World tabloid newspaper in an interview.

Blair told the newspaper he is making "sure anti-terror investigators are not affected" by the criticism.

"I have told them 'This is not your problem'" Blair reportedly said. "For myself, it's a job I have to do. And I am not going to be distracted from the main job which is finding the terrorists."

Blair told the newspaper he did not know the Brazilian was not connected to the attempted bombings until 24 hours after he was shot.

"Somebody came in at 10:30 (Saturday) and said the equivalent of 'Houston we have a problem,'" Blair was quoted as saying.

"He didn't use those words but he said: 'We have some difficulty here, there is a lack of connection,'" Blair said. "I thought, 'that's dreadful, what are we going to do about that?'"

London's Metropolitan Police said Saturday that it had reviewed the use of deadly force against suspected terrorists following Menezes' killing, and had made only minor changes.

A police spokeswoman declined to discuss details of the changes in Operation Kratos, the force's name for what British media call a "shoot to kill" policy.

Meanwhile, Britain also reportedly reduced the official level of threat for the first time since the July 7 bombing. The Sunday Telegraph reported that intelligence officials had reduced the threat level from the highest rating of "critical" down to "severe general" because there was no specific intelligence of an imminent repeat of attacks.

No one from the Metropolitan Police could be reached Sunday morning to comment on the report.

Blair has said he will not resign over Menezes' killing, which he called "tragic and appalling" and said the police have taken full responsibility for. Britain's top security official, Home Secretary Charles Clarke, who is responsible for policing, said Saturday he had full confidence in Blair.

Blair has denied there was any police cover-up or attempt to block the Independent Police Complaints Commission's investigation now under way. He also criticized the media for concentrating "on the death of one individual when we have 52 dead people from all faiths and communities in London and from abroad," the News of the World reported.

Recently leaked documents from the official complaints commission investigation into Menezes' killing appear to contradict original statements by police that the Brazilian had been dressed oddly and was behaving suspiciously.