Police officers in Manchester and Glasgow will provide security at Games venues following staff shortages at the contractor G4S.
Greater Manchester Police said it would provide officers to fill gaps in security for Olympic football matches at Old Trafford.
The announcement followed reports that only nine G4S recruits out of a possible 140 turned up for a training session to provide security in Manchester last week.
"The decision was taken as part of [our] contingency planning process and will ensure a significant police presence is in place," said the Assistant Chief Constable, Terry Sweeney.
Officers from the Strathclyde force are also taking over responsibility for day-to-day Olympic security from G4S for football matches at Hampden Park in Glasgow.