City councillors have asked colleagues at County Hall to create 20mph zones in every residential street in Oxford.

During recent years, a number of 20mph zones have been introduced but the proposal of Paul Sargent, Conservative group leader on the city council, is far more ambitious.

Keith Mitchell, leader of the Tory-run county council, said the scheme had not been properly costed by the highways department, or approved by the cabinet.

But he added: "We now need to decide if it is feasible and get detailed advice from our officers.

"In order to have a blanket order covering 20mph zones, we would need extensive public consultation.

"This is a serious request from our friends at the Town Hall, so the cabinet will have to take it seriously."

Ian Hudspeth, the county council's cabinet member for transport, added: "It is always difficult to enforce a 20mph zone, but ultimately that responsibility is down to the police.

"A child will suffer more serious injuries if he is hit by a car travelling at 30mph instead of 20mph. If a 20mph zone is established, I would hope that 10 out of 10 drivers would respect it.

"We need to find out if we have the money to do this."

Mr Sargent said: "We have listened carefully to calls from residents for 20mph limits in residential areas to be the norm.

"Most of the streets in Oxford were designed for an age before the motor car was invented.

"We will be looking for 20mph limits to bring real improvements in road safety."

Mr Sargent said the Conservative group hoped that driving speeds could be sufficiently reduced by the 20mph zones to remove the need for speed humps.

The 20mph limit would not apply to major routes in Oxford such as Woodstock, Banbury, Marston Ferry, London, Cowley, Iffley, Abingdon and Botley roads.

Jean Fooks, the Liberal Democrat city councillor for north Oxford, said: "I came up with this idea a few years ago and it became official city council policy, but the county council said they were not convinced it would work.

"The Tories are simply picking up old ideas and dressing them up as new ones."