Thieves who target parking ticket machines in Oxford have cost council taxpayers at least £56,500.

In 2002, £5,500 in cash was taken, but last year the amount rose to £31,000. The council has now decided to fit new security locks to 100 machines, 40 of which have been broken into, and this is costing £20,000 in total.

The cost to the council in terms of lost revenue when machines are out of action has not been calculated, but when machines were out of commission in St Giles in December, where there are 145 spaces, the council was losing £3,000 a day in parking revenue. All 12 machines in St Giles are now back in use.

David Robertson, the council's executive member for transport, said machines in Blackhall Road and Merton Street were broken into after New Year. They are the only machines still out of action.

He added: "Breaking into parking machines appeared to be the novel idea of 2003.

"It seems to have come over from Europe and has been happening all over the country. Thieves were drilling into the drawers to get the small amount of cash in the machines, but these new locks will make that virtually impossible.

"Some people might see a parking machine being broken into and say 'good luck to them', but at the end of the day, this is costing all of us.

"I understand there have been arrests and convictions following some of the break-ins but we will continue to do all we can to ensure we are on top of the problem."

Mr Robertson said that machines would now be emptied twice daily.

Last month the locks on 11 machines in St Giles and Great Clarendon Street, Jericho, were smashed, making it easier for thieves to steal cash. Machines in Keble Road and Mansfield Road were also hit.

Before Christmas, drivers got an unexpected free parking bonus when parking attendants were told they could not enforce parking regulations if machines were not working.