Bangkok, July 12 : Manchester United striker Wayne Rooney suffered a hamstring injury during the team's pre-season tour to Asia and will now miss a month's action.

He flew back to England Thursday and will sit out from the team's three-week-long tour to Bangkok, Japan, Hong Kong and Sydney.

Rooney wrote on facebook describing himself as "gutted" at having to miss out on the chance to play for the reigning Premier League champions under their new manager David Moyes, reports Guardian.

Rooney, who's future with the Manchester club is unsure after months of transfer speculation, is likely to miss the beginning of the English season.

In a statement, Man United said, "Following a scan on a hamstring injury sustained in training, it has been decided that Wayne Rooney should return home immediately. He will be unavailable for selection for a month."

Speaking to MUTV, United manager Moyes Friday admitted that the Rooney suffered the injury before he boarded the 12-hour flight to Bangkok Wednesday.

United will start their title defence Aug 17. They are also scheduled to face Wigan Aug 11 in the Community Shield.

Rooney is also doubtful for England’s friendly against Scotland Aug 14.(IANS)