Thames Valley Police must spend an extra £400,000 on mobile phones for officers because the force's new Airwave radio system is so far behind schedule.

The Airwave system will be introduced in July -- 18 months later than planned.

It will replace the current out-dated police radio system which has poor coverage in some areas and allows criminals to eavesdrop using radio-frequency scanners.

But the force said it also needs to buy new mobiles for officers to phone in crime reports direct from incidents to new police call centres, which are being introduced next year.

This will save officers time by cutting down on paperwork and bureaucracy. Information will be put directly on to the system by a trained operator.

Chief Constable Peter Neyroud said: "We can't afford to have a gap where we can't deliver. We are trying to free up officer time and reduce bureaucracy. I can't afford to wait another eight, nine, or ten months while we wait for Airwave to be up and in operation. We are plugging a gap."

He said the police would seek to recover the £400,000 from mmO2, the company which supplies Airwave.

The Airwave system will take several months to test across the Thames Valley, and Mr Neyroud did not think it was reasonable to expect staff to use their own mobiles in the meantime.

Lord Bill Bradshaw, an Oxfordshire representative on the police authority, said police needed to process crime report information more quickly and agreed the force should try to recover the £400,000 from mmO2.

He said information should be logged within 24 hours, but the force was in some cases a long way behind that target.

Airwave spokesman Mark Ede said: "The Airwave programme is a national roll-out going to 53 police forces in England, Scotland and Wales.

"The exact time of the delivery of the service is subject to negotiation with the individual forces and the Police Information Technology Organisation, which manages the contracts on behalf of the Home Office."

Barry Patman, chairman of Thames Valley Police Authority's information and computer technology committee, said buying extra mobiles would ensure all officers had a means of communication.

He said: "The radio system we have currently got is obsolete. We can't acquire any additional handsets, and because we were expecting Airwave to be delivered, we haven't ordered any.

"We have even looked into the the idea of going to other forces that have Airwave to see if their old radios are still available. But unfortunately there's a compatibility problem."

Insp Martin Elliott, the chairman of the Thames Valley Police Federation -- the police union -- said forces introducing Airwave had all experienced delays.

"It would be nice to be in the vanguard of IT delivery as opposed to playing catch-up," he said.