The Rugby Football Union has launched an investigation into Sale's Covid management after the club's 19 positive cases threw the end of the Premiership season into chaos.

Sale's match with Worcester has been moved to Wednesday, while Gloucester against Northampton was cancelled.

"The RFU is undertaking an independent audit of areas including the track and trace processes," said a spokesperson.

A win for Sale would see them reach the play-offs instead of Bath.

However, there remains major doubt over whether the rearranged game can go ahead, with Premiership rivals seeking clarity over the source of the outbreak.

Meanwhile, both the health authorities and Worcester will need to be convinced the fixture can proceed safely.

"Two or three [positive] tests, I can understand, but something major has happened for them to have 19 [positive] tests," Bristol boss Pat Lam told BBC Radio 5 live.

Sale boss Steve Diamond told BT Sport on Sunday evening his club had followed all the correct protocols, and denied claims his players had gone out partying following their Premiership Rugby Cup victory over Harlequins on 21 September.

"The Professional Game Board agreed a minimum standards framework for the season re-start, including the ability for sanctions in the event of any breaches of the framework," added the RFU.

Meanwhile Northampton Saints have reacted angrily to suggestions from Premiership Rugby that they failed to register players in order for their game at Gloucester to go ahead.

Saints say they tried to bring in extra playing resources, but were prevented from doing so by the governing body.

Contact tracing rules meant a number of Northampton players were forced to isolate after playing Sale in midweek, meaning they were unable to fulfil the fixture at Kingsholm, with Gloucester awarded a 20-0 win.

"We asked for permission to register loan players beyond the normal deadline in order that we could attempt to complete our fixture against Gloucester, as planned, on Sunday," said a Northampton statement.

"We were advised that this dispensation would not be granted. We therefore had no option to bring in additional players as cover."