Super Aguri's Formula One future looked to be in jeopardy on Wednesday after would-be purchasers of the struggling Japanese team put their takeover on hold.

A team source told Reuters that Honda-backed Super Aguri had received an official letter from the Magma Group saying that the deal was delayed.

There was no immediate comment from Magma, who had hoped to finalise the purchase by the end of last month. The Super Aguri source, who declined to be named, said talks were ongoing but there was now a real risk that the tail-end team would not be able to race in next week's Spanish Grand Prix.

The team have not joined others in testing at the Circuit de Catalunya this week.

The cars and spares are due to be flown to Barcelona tomorrow for the first race of the year in Europe after three long-haul rounds.

"This could mean that we don't go to the race," said the source.

"Maybe we need a bit more backing from Honda to get us to Barcelona. Our future could be in Honda's hands now, and Bernie's I suppose," he said, with reference to Formula One commercial supremo Bernie Ecclestone.

However, another F1 source said that the deal remained alive but had hit problems because part of the financial backing had not materialised.

Super Aguri, whose drivers are Japan's Takuma Sato and Britain's Anthony Davidson, said last month that they had reached agreement with Magma.

"Magma has also reached agreement with Honda regarding technical cooperation and engine supply to Super Aguri," it added.

Magma Group is run by Martin Leach, a former president of Ford Europe as well as ex-chief executive of Maserati and ex-managing director of Mazda Japan.

The company's Ultramotive division are based at the Leafield facility in central England used by Super Aguri and the now-defunct Arrows before them.

Super Aguri, founded by former racer Aguri Suzuki, finished ninth of the 11 teams last season.