Speculation on a possible move to Real Madrid or a return to former club Juventus has been mounting since a season in which Pogba faced criticism at times for his performances with United.

The 26-year-old told reporters in Tokyo while attending an event held by sponsors Adidas that it could be time to leave Old Trafford.

"Like you said, there is a lot of talking and a lot of thinking as well," the France midfielder said.

"For me I have been for three years in Manchester and have been doing great; some good moments and some bad moments, like everybody. Like everywhere else.

"After everything that happened this season, with my season being my best season as well... I think for me it could be a good time to have a new challenge somewhere else.

"I am thinking of this: to have a new challenge somewhere else."

United boss Ole Gunnar Solskjaer has made clear he will start to rebuild his squad this summer, but Press Association Sport understands the club expect Pogba to still be their player next season.

Pogba was re-signed by United in the summer of 2016 from Juventus for a then world record transfer fee of STG89 million ($A163 million).

He had spent four years with the Italian club after being sold to them by United for STG1.5 million in 2012.

Australian Associated Press