An environmental group wants trees to be placed in two of Oxford's most historic streets to give the city centre a new image.

Forest of Oxford says trees in Cornmarket Street and Broad Street would make the city more welcoming for visitors.

But the city council, which helps fund the group, said it would not investigate the proposals. A similar suggestion by city councillors two years ago was rejected when Thames Valley Police said the foliage would block sightlines for CCTV cameras.

Oxfordshire County Council also claimed tree roots could damage pipes and cables laid under the surface of the road.

Forest of Oxford said its new plans would solve this problem.

The group wants three ash trees, in heavy planters to restrain the roots, to be placed in Cornmarket Street as part of the current improvement scheme and five or six trees in Broad Street.

Group co-ordinator John Thompson said: "Cornmarket Street is really a rather sad street and needs to be brought back to life after the pavement fiasco.

"Broad Street is one of the most-famous and most-visited streets in the city and I believe it's rather a disappointment for people.

"It could be turned into a lovely Parisian-style boulevard, with a few attractive trees and chairs outside cafes for people to admire the views."

Colin Cook, the city council executive member for planning, said he believed there was enough foliage provided in streets in the city centre by the hanging baskets put up as part of the annual Oxford in Bloom campaign.

He added: "The idea is to reduce the amount of street furniture clutter and improve access for disabled people. The presence of trees or raised beds would undermine this."