Cllr Paul Murphy told Granada Reports the policing operation at the Worsley Marriott will cost £30,000 a day.
It includes 28 constables and four sergeants. G4S should have had 58 of their staff on the site, but only about a third turned up for the lock-down.
A Merseyside representative of retired police has attacked G4S, saying the security firm told them they are "surplus to requirements".
Armed police have been called in to plug a shortfall in security at a hotel used by Olympic athletes in Manchester.