Manchester United's management of their £351m debt faces a further obstacle after the club pledged to bow to manager Louis van Gaal's demands to downsize future pre-season tours, thereby cutting their commercial revenue.

Van Gaal has criticised this summer's tour of the United States, presented by current principal sponsors Aon, which sees the club play LA Galaxy, AS Roma, Inter Milan and Real Madrid across 10 days, but says future pre-season plans will be scaled back.

United played matches in Thailand, Australia, Japan and Hong Kong last summer to help cement recent sponsorship deals which contributed to the club posting record commercial revenue figures of £42.8m in the three months ending March 2014.

And though United have granted Van Gaal's request to organise low key fixtures in the future, the loss of significant revenue will hinder the club's hopes of extinguishing their much-screwtinised debt inflicted upon them by the Glazer family's takeover in 2005.

The criticism of the club's commercial commitments could also affect the clinching of future deals, though, Aon will be replaced by Chevrolet as main sponsors at the end of this season while earlier this month United agreed a world-record £750m deal with kit manufacturer Adidas.

Executive vice-chairman Ed Woodward admitted on Tuesday that the successful management of United's debt was possible due to their commercial success, which have seen profits rise by nearly 20%.

The 20-time champions of England will lose out on an estimated £50m this season after failing to qualify for the Champions League, however increased Premier League television money will offset those loses.

Woodward has said the club's debt will not obstruct United's dealings in the transfer window, with Ander Herrera and Luke Shaw having joined this summer however the club will suffer a drop in commercial success after accepting the demands of Van Gaal, who fears for the club's preparation ahead of the new season.

"More or less. We have to prepare for the season and when you have commercial activities and dreadful distances, having to fly a lot and the jet lag, it is not very positive for a good preparation," Van Gaal said on the eve of United's first pre-season game against LA Galaxy.

"The tour was already arranged and I shall adapt and United will do everything to apply to my rules, but I have said that already. This is the first time I am late for a press conference, but it is the Los Angeles traffic, so I am sorry for that."

"I hope that [next summer's tour will be shorter], but they have already said that to me and I am very confident that it shall be."

The 62 year old Van Gaal hinted at a wish to challenge United's commitment to their commercial obligations upon his unveiling as manager last week and it comes as no surprise given his uncompromising reputation that he has stood up to the Old Trafford hierarchy.

He said last week: "This club is also guided in the commercial way and we have to fulfill that also. And that's not always possible to fulfill both commercial and football. That's my big challenge after two days. Maybe it will be changing after the US tour, but I don't think so!"