THE English Football League has confirmed it will extend its invitation to compete in a revamped EFL Trophy competition to as many category one academy sides as required until all 16 places have been filled.

Sixteen category one clubs have been invited to join the 48 sides from League One and League Two in an attempt to rejuvenate the competition - formerly known as the Johnstone's Paint Trophy - for the 2016/17 season.

But of that number, several have opted not to enter their academy sides, with Arsenal, Tottenham, Chelsea and Manchester City all believed to be ready to snub the offer.

Liverpool and Manchester United are also understood to be leaning towards rejecting their invitation - leaving the controversial overhaul of the EFL Trophy in trouble.

But other category one academies are set to be given the chance to take part in the competition - which will feature new group stages due to begin next month - in place of those who turn down the opportunity.

An EFL spokesman said: "The EFL is currently awaiting responses from a number of clubs that have been invited to take part in this season's EFL Trophy. Already a number of clubs have accepted our invitation to take part.

"In any instances where clubs do decline, we will issue invitations to other clubs with category one academies in the order in which they finished in the 2015/16 domestic league tables. We will then confirm the final line-up of competing clubs once we have received a full set of responses."

The EFL had hoped to have all responses from the 16 original invited clubs, 15 of them Premier League sides and the other recently-relegated Newcastle, by Monday - although it is understood no official deadline for a response was put in place.

With the top grading of academy status the qualifying criteria, it means Sky Bet Championship sides will be invited over those Premier League clubs who do not meet the standards.

The likes of Norwich, Aston Villa, Brighton, Derby, Wolves and Blackburn are therefore expected to be asked to enter, while of the initial 16 sides Everton, Southampton, Stoke, Sunderland, Swansea and West Brom have all confirmed to Press Association Sport their intention to compete.

The move to invite academy sides to play alongside lower-league outfits has already attracted criticism from clubs and fans worried about the possible introduction of Premier League B teams into the EFL, with top-flight sides able to field five players older than 21 in any EFL Trophy fixture.

The reformatted tournament will see 64 teams split into 16 groups of four, on a north/south regional basis, each containing an invited club and they will play each other once, with the invited club playing one game at home.

Teams will earn three points for a win and a point for a draw, but if the scores are tied after 90 minutes an extra point will go to the winner of a penalty shoot-out.

The top two from each group will then proceed to a regional knockout round of 32, with the rounds of 16, eight and four being free draws.

These will all be single ties and will be settled by penalties after 90 minutes, although that may change for the semi-final and Wembley final.

It remains unclear whether Premier League champions Leicester, as well as Middlesbrough, West Ham and Newcastle are willing to be involved.