London ? British lawmakers voted Wednesday to ban glorifying terrorism, giving Prime Minister Tony Blair a badly needed victory on a measure he said was key to preventing future attacks.

The House of Commons approved the ban 315-277, sending it back to the House of Lords, which had struck down the term “glorification” earlier this year, saying it was dangerously vague.

The two chambers must reach agreement for the measure to become law.

Blair said the vote sent a “signal of strength” and would allow authorities to prosecute demonstrators such as those he said carried placards espousing violence during recent London protests against a Danish newspaper’s publication of cartoons of the Prophet Muhammad.