The Super Aguri team are seeking an investor before the Spanish GP
The future of the Super Aguri Formula One team is in doubt again after investors pulled out of a takeover.
Britain's Magma Group had been expected to complete the buyout at the end of last month, but they have now told the Japanese team the deal is off.
It is believed Magma's financial backers, Dubai International Capital, are having second thoughts.
Super Aguri are seeking new investors but warned they may be forced out of the Spanish Grand Prix on 27 April.
A statement by the team said: "Super Aguri confirms that it has been informed by Magma Group, the potential purchasers of the team, that its investors no longer wish to fund the intended acquisition.
"It is with deep regret that [team owner] Aguri Suzuki is now forced to consider the future of the team, however negotiations with other parties continue."
A team spokesperson confirmed they may not have financial backing in place to compete in Barcelona and the team have already skipped testing at the Circuit de Catalunya this week.
The Oxfordshire-based team raced in the opening three Grands Prix after securing last-minute backing through the automotive industry consultancy and innovation group Magma.
But DIC, who were embroiled in a potential takeover of Liverpool Football Club, are now reconsidering their level of investment.
The team need to find a solution fast
BBC Radio 5 Live's Formula One commentator David Croft explained the Dubai investors may just be negotiating their position.
"It could be that DIC are stalling to lower the price-tag for a buyout, which is worth around £50m," he said.
"The majority of that money goes to Honda F1 who have been building and supplying the cars for Super Aguri.
"If Honda can be persuaded to lower the price then maybe a deal can be resurrected but the team need to find a solution fast."
Super Aguri, who are bottom of the constructor standings, have been using Honda engines and have also been supported by the Japanese manufacturers.
However, under new regulations which come into force in 2010, teams will no longer be able to make custom cars for other outfits.
Honda are also determined to focus on their own development programme next season and insist they will not bail out Super Aguri.
A spokesperson for Honda said: "We intend to continue the present structure of our support for Super Aguri.
That means Super Aguri, who have Britain's Anthony Davidson in their team, now need to find a new investor or ask Formula One supremo Bernie Ecclestone for assistance.