Cristiano Ronaldo should have told Manchester United he wanted to leave at the end of last season rather than drop a July bombshell, according to former Liverpool star Jamie Carragher.

Superstar Ronaldo returned to Old Trafford last year, having enjoyed a remarkable career in 12 seasons away with Real Madrid and Juventus, but widespread reports on Saturday said the 37-year-old wants to leave again.

He is said to want to play in the Champions League, according to The Times, which first reported the news, and United cannot offer that after a disappointing sixth-placed finish last season.

The Portugal striker has been a mainstay in that competition throughout his career, and the prospect of being away from the frontline of elite European football would be a step down.

New United manager Erik ten Hag will target a return to the Champions League, but that is at least a year away, and veteran Ronaldo does not have time to waste.

Unless Ronaldo has been given unexpected information about his role at United in the new season, Carragher said he could not understand the timing of his apparent request to move on.

Carragher sparked a debate with former United captain Gary Neville on Twitter when he wrote: "Ronaldo did exactly what I thought he would do, score goals but make the team worse. The transfer request also kills the idea he turned down Man City because of his love for Man United."

That was a reference to the saga that saw United seemingly pip Manchester City to the signing of Ronaldo last August, when Alex Ferguson appealed to his former star player to return to the Red Devils.

Carragher's comments triggered a rebuttal from Neville, who said: "I get it, you’re full of yourselves but he can turn down City for United because he likes them more and still want to leave this summer. He left before but still loved the club. Enjoy Saturday night and your short period of success."

Carragher, who has seen Liverpool rack up a string of trophies during a lean recent period for United, did not leave it at that.

"City didn’t want him you [clown] and you're the same fella who kept saying it was like Elvis had arrived in Manchester! Elvis has left the building," Carragher replied.

Carragher added: "Also, why now? Has ETH [Erik ten Hag] told him he is not part of his plans or will play a limited role?? Surely the end of last season was the right time to tell the club."

Ronaldo scored 24 goals in all competitions last season, including 18 in the Premier League.

United finished with their lowest points tally in the 30-year history of the Premier League, a competition Ronaldo won three times during his first United stint from 2003 to 2009.

Five-time Ballon d'Or winner Ronaldo has recently been linked with United's domestic rivals Chelsea and Jose Mourinho's Serie A outfit Roma. The Italians would be unable to offer Champions League football in 2022-23, but Chelsea could, having finished third in last season's Premier League.