Premier League chief executive Richard Masters has written to clubs to stress the importance of adhering to strengthened coronavirus protocols.

Masters warned that clubs should prepare for more matches to be postponed or rearranged at short notice – as the PA news agency understands coronavirus-hit Aston Villa are in discussions about the potential rescheduling of Sunday's visit of Everton.

"It is already clear that we must do all we can to efficiently utilise all available calendar slots, given there have been three significant Covid-19 outbreaks at clubs to date and we should therefore realistically plan for the fact that there may be more," Masters wrote in his letter.

"Inevitably, requests for postponements will be at short notice and present difficulties for all parties and we appreciate clubs' ongoing flexibility in helping us achieve our collective objectives."

Fulham's Scott Parker called the decision "scandalous" to rearrange a match for them against Tottenham on Wednesday as Villa could not fulfil the fixture due to their training ground being closed.

Spurs boss Jose Mourinho had been equally critical when the original game with the Cottagers was called off at a few hours' notice on December 30 but Masters said judgements had to be made "within tight timeframes".

In terms of adhering to the new protocols sent to clubs last week – which includes avoiding hugging, handshakes and swapping shirts – Masters added: "We are fortunate to be able to continue to play and bring our competition to fans at home and around the world.

"This brings justified additional scrutiny and the Premier League must take the lead in setting the right example to follow.

"The FA has written to all clubs remaining in the FA Cup on similar terms, after disappointing and concerning scenes at some third round FA Cup matches."

Villa's game against Everton has already been put back 24 hours in the hope it would allow more time to fulfil the fixture after the club's training ground was closed last week following positive tests for nine players and five staff.

It resulted in their youth team having to face Liverpool in their FA Cup third-round tie on Friday and with the club having to sit out their midweek slot this week, having already been two matches behind the majority of their top-flight rivals, having to fit in a third rearranged game would push the already stretched programme further.

Meanwhile, Grimsby have been sanctioned by the EFL – understood to be a £4,800 fine suspended until the end of June – for several breaches of Covid-19 protocols, which included former manager Ian Holloway playing darts with members of his squad.

The League Two club were forced to request the postponement of three matches earlier this season.

EFL chief executive Trevor Birch has written to clubs warning the competition would come under pressure from the Government to stop playing if they "continued to flout the rules".

"Throughout the pandemic, football has provided a glimmer of hope for many millions of people affected by restrictions but we all understand the scrutiny the game remains under and we will come under extreme governmental pressure if we continue to flout the rules," Birch wrote.

"While football is permitted to continue the actions of all participants will be clearly under the microscope, whether this be in technical areas, dugouts, or in relation to general behaviour and interaction between players on the pitch and staff off it."

The EFL reported 11 further positive cases from last week's round of testing, taking the total number of positive tests to 123 for the week, and Brentford's Championship matches against Bristol City and Reading have been postponed due to recent positive tests.

There were 15 positive tests reported from 942 carried out by the Barclays FA Women's Super League and FA Women's Championship last week, while the FA Youth Cup has also been temporarily suspended.

Meanwhile, Premier League side Brighton's Amex Stadium is to be used as a training centre for those who have volunteered to administer coronavirus vaccine.

A range of sports venues are now involved in the nationwide vaccination rollout programme, including Lord's cricket ground and Manchester City's Etihad Campus.