Victor Valdes hit back at Manchester United manager Louis van Gaal Thursday after he claimed the goalkeeper had snubbed the club's reserves last season and would be sold.

Van Gaal said on Wednesday Valdes would be shown the door at Old Trafford after refusing to play for United's second team.

However Valdes, who was not included in United's squad for their four-match US tour, responded to van Gaal's comments on Twitter on Thursday.

The former Barcelona star posted a photo montage showing three matches he played in last season for United's Under-21s after signing for the club in January.

Another photo showed a picture of Valdes celebrating with smiling United team-mates.

The photos were posted with a caption "....? #respect."

On Wednesday van Gaal told journalists in Seattle Valdes was being sold for failing to follow the club's philosophy.

"When you are not willing to follow the principles of the philosophy, there is only one way, and that is out," van Gaal said.

Asked if that meant United planned to sell Valdes, van Gaal replied: "Yes."

Valdes was invited to train with United in October 2014 as he sought to work his way back to fitness from a knee injury.

He signed in January and made his first start in the final game of the season against Hull, keeping a clean sheet.

United open their International Champions Cup campaign against Mexico's Club America in Seattle on Friday.