David Cameron was "negligent" to give his multiculturalism speech on the day of an English Defence League (EDL) march in Luton, according to one of the town's MPs.
Labour backbencher Gavin Shuker used a comment piece for politics.co.uk to attack the prime minister's speech, in which Mr Cameron blamed home-grown terrorism on the laissez-faire system of British immigration.
The address to the Munich security conference came as up to 3,000 EDL protesters gathered in Luton. Some claimed Mr Cameron's comments could be interpreted as supporting their march.
"Either David Cameron did know about the timing of Saturday's march, in which case he was negligent in not informing the police and local authority of his statement in the days before," Mr Shuker wrote.
"Or, if he didn't know, he was negligent in giving the EDL just the publicity they crave through a speech that should have been properly researched and timed.
"Cock-up or conspiracy: either way the timing of Cameron's speech served to give succour to the EDL extremists on an incredibly challenging day for both police and residents in our town."
Bedfordshire police deployed 2,000 officers to police the march in their biggest ever operation. It did not trigger the wider unrest many locals had feared.
Mr Shuker said community cohesion issues needed to be addressed but blamed extremist voices, like those of the EDL, for drowning out reasoned debate.
"That is the challenge - to foster a measured debate on community cohesion," he added.
"That can only be done with thoughtful and well-timed interventions. If only Saturday's speech had fulfilled both those criteria. Instead, EDL supporters were overhead claiming that Cameron's speech was their big win."