Some traders at Oxford's Covered Market are facing near-double rent increases following a ruling by an independent arbitrator.

Fifty-four traders at the historic market appealed against the rent review by the council, and the Covered Market Traders Association is now studying the judgement, which includes increases ranging from zero to 80 or 90 per cent.

Association chairman Richard Alden said traders would seek further negotiation with the council following the ruling because such large increases would put some businesses at risk.

He said: "In the present economic climate, the high increases set for some businesses could make them unviable.

"I hope further negotiation can take place with the council. If councillors take a hard-nosed approach, desperately poor relations could build up between tenants and the council, and between tenant and tenant, which would be unfortunate in the circumstances."

Mr Alden said opening the market all year round for Sunday trading - which now takes place only in December - could be high on the agenda if talks with councillors remained positive.

He said: "In a recent referendum, about 60 per cent of the traders were in favour of it and Sunday is now one of the biggest trading days of the week.

"The charges traders would face for opening on Sunday is something that will be discussed as part on an ongoing review."

Earlier this year, the arbitrator ruled on four out of 54 cases, ordering rent increases ranging between 28 and 51 per cent but rents for the remaining 50 businesses have now been settled.

A 3,500-signature petition, which aimed to save shops in the Covered Market from going bust, was presented to city councillors last month.

Referring to arbitration on the 50 stores, a spokesman for the council said there had been a "wide variation in the level of rent alterations, in order to reflect the size of the various units and their position within the market".

Mr Alden said he did not know which businesses were facing what level of increase and the council would not comment.

Bob Price, leader of the city council, said: "The results of the independent arbitration have been positive for both the council and the traders.

"The council is committed to continuing to work with the traders and plans to establish meetings to discuss regular funded maintenance and improvement.

"A review of the management of the market will also be conducted, including re-examining Sunday opening."

Sally Davis, of the Cake Shop in the market, said the business was being asked to pay a rent increase of 51 per cent.

She said: "We are trying to do more advertising on the corporate side and bring in more website orders."