But both players say they are "not shutting the door completely".

Leicester City striker Vardy - who has won 26 international caps - says he first told Southgate of his intentions at the World Cup in Russia.

"This has been on my mind for a while," the 31-year-old told the Guardian.

"I'm not getting any younger and you can see, to be fair to the gaffer, he wants to make it more youthful, which obviously had its benefits during the World Cup."

Vardy, who made his England debut against the Republic of Ireland in June 2015, made four appearances for England at this summer's World Cup, where they reached the semi-finals.

He has told Southgate he also wishes to concentrate on his club football and his family.

"Gareth said that he felt I still had a lot to offer, and we've not shut the door completely," said Vardy, who scored seven goals in an England shirt.

"If the worst came to happen and everyone was injured, then obviously I wouldn't say no."

Chelsea defender Cahill, 32, scored five goals in 61 appearances for England, having made his debut in 2010, and captained the side on several occasions.

He made just one appearance at the World Cup, during England's 1-0 group stage defeat by Belgium.

"I can see it is now going to a younger generation and I think it is the perfect time for me to take a step back," Cahill told Chelsea TV.

"I've been hugely honoured to play for my country and I would never shut the door.

"I've said that if there are injuries in the future and I'm needed to come and play then, of course, I'm available."