Van Gaal has reportedly agreed basic terms with United and it was widely expected that his appointment would be announced on Thursday.
However, with the finer details of the contract yet to be agreed and Van Gaal preparing his Netherlands side for a weekend friendly against Ecuador, the deal will now be announced early next week.
Earlier in the week, the Dutch coach grew frustrated with reporters’ questions regarding his situation.
"I'm here as Dutch national team coach, not the future Manchester United coach," Van Gaal said.
"You must wait until the process is complete. If you want to know more, then you must be at Manchester United or any other club," he added in a testy exchange with reporters.
United's interim manager Ryan Giggs was photographed leaving a hotel in the Dutch town of Noordwijk on Wednesday, where it is understood the 40-year-old had a meeting with Van Gaal.
Giggs' playing contract expires in June and he is expected to be offered a senior coaching role, though it is not known whether he intends to keep playing next season.
TWEET: Van Gaal announcement won't be until early next week now. No issue, just few minor bits to resolve. See Times website #mufc
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