Ford is aiming to whittle down the number of potential buyers for its Jaguar and Land Rover brands by the end of next month.

The US automotive manufacturer is believed to be seeking a tentative deal by September 30, suggesting it is looking for a preferred bidder to emerge from the mixture of private equity and automotive companies which have expressed interest.

It may not have ruled out a shortlist of two, leaving open the option of a competitive auction, according to sources.

Ford has declined to comment on detailed progress following its announcement late last month that it had received a number of expressions of interest in the two marques and that it was impressed by the "strength and quality" of the interested parties.

The company has said it is exploring the possibility of a sale but has been careful not to commit itself to a timetable and is stressing that no final decisions have been taken. The US carmaker is understood to be reluctant to be drawn into an open-ended process, having imposed an informal deadline on expressions of interest in July.

Jaguar and Land Rover are said to have attracted interest from Tata, the Indian company which found itself involved in a cliff-hanging auction for the steelmaker Corus, as well as private equity companies, including TPG, Cerberus, which has just bought Chrysler, and One Equity, where Jacques Nasser, who bought Land Rover for Ford, is closely involved. India's Mahindra and Mahindra is also thought to be among the bidders.

Figures from the Society of Motor Manufacturers and Traders yesterday showed that Land Rover has increased its UK sales so far this year, from 26,683 to 27,501. However Jaguar's sales are down from 14,312 to 11,520.

Overall, UK car sales rose last month, despite rising interest rates, with registrations increasing by the highest level since January. Just over 176,000 new cars were sold in July, up 4.9% on the same month in 2006.