Two senior Brazilian officials arrived Monday to meet with British government representatives and an independent watchdog agency investigating the police shooting of a Brazilian mistaken for a potential suicide bomber.

Pressure is mounting on London's Metropolitan Police (search) and its chief, Commissioner Ian Blair, over allegations of serious failings by police before the death of Jean Charles de Menezes (search) one month ago.

"We are here to see how the investigation works," Wagner Goncalves, the country's deputy attorney general, said on arriving with Marcio Pereira Pinto Garcia, a high-ranking Brazilian Justice Ministry officer.

Undercover police tailed Menezes to an Underground train and shot him seven times in the head and once in the shoulder on July 22, the day after failed bomb attacks on London's transit system. Two weeks earlier, similar attacks killed 52 commuters and the four homicide bombers.

New reports emerged last week that appeared to contradict initial assertions that Menezes had aroused suspicion by wearing a bulky jacket despite the warm weather and running from police.

Blair has insisted police have assumed full responsibility for the shooting and has vowed to remain in his job despite the increasing criticism. On Sunday, he won the backing of Prime Minister Tony Blair's (search) office and Deputy Prime Minister John Prescott, who is in charge while Blair is on vacation in Barbados.

Menezes' mother, Maria, told the British Broadcasting Corp. on Monday that she wants the police who shot her son to be punished.

"They ended not only my son's life but mine as well," she said from Brazil.

Supporters of the Menezes family planned to hold a vigil Monday outside Blair's Downing Street office.

The Brazilian officials said they looked forward to meeting Wednesday with members of the Independent Police Complaints Commission, which is investigating the shooting.

"The idea is to understand better how the system works," Garcia said.

Scotland Yard refused to comment on reports that Ian Blair would not meet with the Brazilian officials and would send a top deputy instead.

Ian Blair told a British tabloid on Sunday that it was only 24 hours after Menezes was shot that he learned officers had killed an innocent man.

"I thought, 'That's dreadful, what are we going to do about that?"' he said, according to Sunday's News of the World newspaper.

Meanwhile, Home Secretary Charles Clarke defended a series of tough new anti-terror measures being introduced in response to the bombings.

The measures make it easier for the government to expel Islamic extremists, bar those deemed to be inciting hatred and close down mosques that promote violence. Clarke said he would introduce "new ways of dealing" with extremist preachers and others who promote hatred.

"We must protect the traditions of tolerance that we have established in this country," Clarke wrote in an editorial in London's Evening Standard.

Britain is seeking pledges that anyone it deports won't face torture at home — agreements that critics say are worthless since torture is believed to be widespread in some of the north African and Middle Eastern countries with which Britain is negotiating.

Clarke defended the agreements, saying they included a guarantee of independent monitoring. He also compared the agreements to U.S. assurances that British suspects extradited to the United States would not face the death penalty.