London Irish have been served a winding-up petition by HM Revenue & Customs over an unpaid tax bill.
The ailing Premiership club were this week given an extended deadline of 16:00 BST on Tuesday, 6 June to complete a proposed takeover.
But on Friday petitions were filed at the High Court against London Irish Holdings Limited and London Irish Rugby Football Ground Limited.
Irish could yet be suspended from the top flight of English rugby.
For the club to avoid suspension, they must complete a takeover or demonstrate they have the funding to operate for the entire 2023-24 season.
The winding-up petition came on the day that the UK government appointed independent advisers to support rugby union bosses as they attempt to preserve the future of the professional game after the failures of Worcester and Wasps last season.
HMRC would not comment specifically on London Irish but a spokesperson said: “We take a supportive approach to dealing with customers who have tax debts and only file winding-up petitions once we’ve exhausted all other options, in order to protect taxpayers’ money.”
As part of the Rugby Football Union’s latest 6 June takeover deadline, the Exiles have been told they must ensure the May payroll for all staff and players is paid in full – with only 50% received so far.
An American consortium is in discussions to take over the the club, who have debts in the region of £30m, but has yet to provide proof of funds to the RFU, as well as other documentation needed for the purchase to be approved.