Football risks another suspension if clubs "continue to flout the rules" in place to limit the spread of coronavirus, the chief executive of the English Football League (EFL) has warned.
Elite sport has been allowed to continue despite a fresh national lockdown designed to slow down the rate of Covid-19 infections.
However, a number of on and off-field incidents, along with an increase in positive test rates among players, means the professional game is under intense scrutiny from the government and the public.
EFL chief Trevor Birch, in a letter to clubs, said football had provided hope for people during the pandemic but would come "under extreme governmental pressure if we continue to flout the rules and guidance in place".
There were high-profile instances of virus protocols being breached by EFL clubs -- those in the second, third and fourth tiers of the English game -- over the FA Cup third-round weekend.
Championship side QPR admitted they should not have allowed former player Eberechi Eze to attend their tie against Fulham, while fourth-tier Crawley's exuberant celebrations after their win against Premier League side Leeds broke social-distancing rules.
"As a result of the emergence of a more virulent strain of the virus, it is more important than ever that all club staff vigilantly follow the processes we have worked hard to develop to keep our competitions on track and avoid a suspension similar to the one encountered in March 2020," Birch said in his letter.
He warned if the EFL felt clubs had not taken appropriate action over breaches, it could impose its own sanctions.
From this week, players and staff at EFL clubs will be tested twice a week.
The EFL announced on Tuesday Brentford's next two Championship matches had been postponed due to recent positive Covid-19 tests, including for manager Thomas Frank.
The Premier League has encountered its own problems with fixtures being postponed, while some top-flight players were heavily criticised for attending or hosting gatherings over the Christmas and New Year period.
London, United Kingdom | AFP