Following reports that London's minority communities were organizing to protect themselves, Home Secretary Jack Straw said residents must not panic.
"Whilst the perpetrators of this violence remain at large there is plainly a risk that they may strike again," Straw told the House of Commons. "We have to meet that threat with vigilance but without panic."
The bombers, are only "likely to be brought to justice with the help of all sections of the community," he said.
David Vaness, the Metropolitan police assistant commissioner, said police feared "a continuing series of vicious attacks," possibly spreading to other cities.
A neo-Nazi organization, Combat 18, claimed responsibility for the nail bomb that exploded Saturday in Brick Lane, the heart of a Bangladeshi community in east London. Seven people were injured.
The same group was among four far-right organizations that claimed responsibility for an April 17 nail bomb that injured 39 people in Brixton, a south London neighborhood with a large Afro-Caribbean community.
"The police are pursuing the investigations of these bombings and the protection of the public with the utmost vigor," Straw said. The bombings are "the No. 1 priority for the whole of the Metropolitan Police Service."
Police and other organizations have offered an $80,000 reward for information leading to the arrest of the bombers.
An Asian group said it will mount its own weekend patrols in Southall, a racially mixed south London district.
"We have suffered a long history of racial hostility... but this is racial terrorism," said Suresh Gover, explaining that 100 volunteers wearing armbands would patrol Southall on Saturday.
Both previous attacks took place on Saturdays. Police said the two attacks appeared linked and were clearly racially motivated.
Britain's Commission for Racial Equality said the bombings were a backlash against an official inquiry into the bungled police investigation of the fatal stabbing of a black London teen-ager in 1993. Five white youths were charged but not convicted in the killing of Stephen Lawrence.
The report, released in February, said the London police force was riddled with racism.
Written by Maureen Johnson
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