LONDON  Britain said Tuesday it was outlawing a radical Islamic group that had incited outrage by planning a protest march through the streets of a town made famous for its somber ceremonies honoring British soldiers killed in Afghanistan.

Alan Johnson, the British home secretary, said the move criminalizing membership in the banned group, Islam4UK, was a “tough but necessary power to tackle terrorism.” The ban, which takes effect Thursday, also outlawed other names used by the organization.

Last week, the British prime minister, Gordon Brown, said he was “personally appalled” by the group’s plans to march through Wootton Bassett, a town 70 miles west of London where residents have lined the streets for more than two years to pay respects to the passing hearses carrying the coffins of British soldiers flown home to a nearby military base.

Islam4UK decried Britain’s action in a statement posted to its Web site on Tuesday, saying that the prohibition of the group was “a clear case of the oppressor and tyrant blaming the oppressed.” On Sunday, the group scrapped plans for the march, which had sought to highlight what it called the “atrocities” committed by British troops in Afghanistan.