Even though it appeared in bullish mood at the launch of its season five calendar last week, the future of the A1 Grand Prix series could be in doubt following news that the British-based day-to-day operations side of the business has gone into liquidation.

Britain's Daily Telegraph newspaper reported that the side of the company responsible for looking after the Ferrari-built and powered cars, which has bases in London and at Silverstone, hadn't been able to pay suppliers, confirming rumours that the series was struggling to make it to its 2009-10 campaign.

"Like many other companies in today's difficult economic environment, we had cashflow problems and we haven't been able to pay [the suppliers]," a spokesperson for A1 Grand Prix Operations Limited told the newspaper, before suggesting that the courts may be poised to appoint an administrator for the company, a subsidiary of British Virgin Islands-based A1 Holdings.

The latest speculation comes at the end of a season in which the series attracted not only the support of Ferrari, but also one of motorsport's most iconic names, in the shape of Andretti Green Racing and third generation racer Marco Andretti, and some of the world's hottest rising stars, including eventual champion Ireland's Adam Carroll. All that, however, could not disguise underlying problems, with events being cancelled and teams not appearing as expected.

Former frontrunner Canada failed to appear at all, despite being listed on the entry, while Pakistan managed one test outing and South Korea just a couple of early race appearances. More significantly, season two champions Germany only contested the second half of the season after apparently being funded through series boss Tony Teixeira, while Great Britain struggled through to the end of the campaign after being propped up by the series once its parent company went into administration.

While the series is trumpeting a possible expansion to twelve rounds in 2009-10, it failed to complete four of the eleven events it had planned in season four - with Mugello falling foul of delays in the Ferrari build programme and both Indonesia and Mexico being canned - the latter twice. Finally, the mystery event that existed under the TBC banner all season simply faded away. Reports that Team New Zealand seat holder Colin Giltrap had funded the airlift of cars and equipment from Sepang to Taupo in order for the NZ round to go ahead prompted the New Zealand Herald to suggest that the end may be nigh as recently as May this year.

"The cancellation of the Mexico round is convenient - albeit valid in its convenience, so to speak," the report quoted former CEO of the Kiwi team, Bob McMurray, as saying, "The A1 people can now save themselves a lot of money by not shipping all the cars halfway around the world for one bloody race. And I'm still not sure A1 wouldn't have found another excuse not to go.

"There's no major sponsor of the series still after four years and there's still no real money coming in. Can it continue? I don't really know. I have my doubts, I have to say, but it seems to continue."

The latest revelation is the most serious yet for the series, which was started in 2004 by Sheikh Maktoum Hasher Al Maktoum, but has repeatedly been rumoured to have over-stretched its financial means. A reported $240m loss was made in the course of the 2005-2006 season alone and, despite costs being greatly reduced since, a vast amount of money has been spent running - and propping up - the championship.

Sheikh Maktoum departed in 2006 as part of a major financial restructuring that was supposed to help the company prepare for a float on the London Stock Exchange, with hedge fund RAB Capital acquiring a majority stake. Chief executive Philip Richards was reported to have spent $150m on an 80 per cent share in the championship, using money from the company's Special Situations arm, but various write-downs in the period since are believed to have reduced the value of the stake to almost nothing. Richards was duly removed from the company in 2008.

While it remains unclear what will happen to the 40 employees at the British-based A1GP arm - it is rumoured that they could be 're-employed through another vehicle' in the next few days - series chief Teixeira remains bullish about the future.

"We are well advanced with all our season five contracts and, for those we have yet to make public, have plans to announce them with events in the specific countries," he said at the unveiling of the first couple of events on the 2009-10 calendar last week, "Our plans for season five include some very exciting new venues that I can assure the teams and the fans will be very popular. While, at the moment, we have submitted a ten-race calendar, I am hopeful of adding one or two more dates in the coming months."

The claims follow a similarly optimistic outlook proffered on the eve of Brands Hatch's season four finale in May.

"The great thing is that we have restructured the series," Teixeira revealed at the time, "Next season, we will be much fitter financially, leaner and with some great sponsors earning value. Our Ferrari link-up with their cars has been fantastic and, next season, we will have twelve races, eight of them paying fees - our best ever."

The latest revelations, however, must cast doubt on the future.