English Football League bosses have been angered by a suspected breakdown in health safety protocols during the Covid-19 outbreak at Leyton Orient.
Senior sources said there was a "clear breakdown" in relation to players staying in close proximity with potential symptoms before it was announced seven had tested positive.
Officials are awaiting the conclusion of two investigations — including one by Public Health England — to decide whether further action is necessary.
On Thursday night the EFL, having already been forced to call off the team's Carabao Cup tie against Tottenham, postponed this weekend’s League Two fixture against Walsall.
Orient denied claims protocols had been breached. The club said in a statement sent to Telegraph Sport: "Club protocols were followed to provide the safest possible environment for players, staff and those we come into contact with at all times. We are working with the relevant authorities to review our current protocols."
The EFL said: "Due to the number of positive cases of Covid-19 within the Leyton Orient squad and the requirement for players and staff to subsequently self-isolate as per EFL and Government guidance, the Club has advised the EFL it considers it is unable to safely fulfil this weekend’s fixture. The circumstances surrounding the postponement will now be the subject of investigation in accordance with EFL Regulations."
Orient are the worst club affected so far by a second wave of Covid-19, which prompted Boris Johnson to postpone the return of crowds for another six months.
The league is hoping to secure £250 million in support payments from the Premier League, which, in turn, is one of 100 national and grass-roots governing bodies to sign a letter pleading for more support from the Government.