The sales of MG Rover assets have run into problems after the Patent Office records states that the TF sports car has already been sold by accident, according to the FT.

SAIC paid £67m for the rights to most of the Rover range of cars and engines last year, but the MG TF and failed SV ‘super car’ were thought to have been excluded from the deal; however, SAIC was listed as the TF’s owner in last week's update of the Patent Office design register.

A spokesman for the Patent Office said the entry in the register counted as proof of ownership of a design. Any reversal of the transfer would require permission from SAIC, as they are now the legal owners.

SAIC refused to comment on its new asset but said it was investigating.

SAIC had not and has still not claimed ownership of rights to the TF, for which it had said there was no market in China. PricewaterhouseCoopers, MG Rover’s administrator, has been trying to sell the rights to and plant for the TF along with the MG brand. Separately, the Qvale company from whose car MG Rover developed the SV reportedly claimed last week it still retained rights to the car.

If the rights to the TF remain in dispute, the issue could affect the already small sums available to MG Rover’s creditors. Companies bidding for assets have been asked to submit final bids in two days’ time and pay a 10% deposit to the administrators – who have not yet commented on the FT report.

The deadline is thought by the FT to be likely to prove difficult for some possible bidders, with Iran, which has expressed interest in buying all of Rover, holding the first round of its presidential election on Friday. Nikolai Smolenski, the Russian millionaire owner of TVR, is said to be awaiting answers from PwC about the sale before going ahead with a bid for the whole business.

However, one bidder told the FT he hoped the deadline would speed up the process and lead PwC to name an exclusive bidder. "We are looking to have a change of pace after Wednesday," he said. But another questioned how serious the deadline was: "They can't even tell you exactly what it is they are selling yet," he said.