The 15-year-old spent a week with United last month, and played for their under-18 side in a fixture against Aston Villa.
And he admitted he enjoyed every minute of the experience with the Old Trafford club, but now intends to train with Arsenal, Everton and Manchester City ahead of a possible move to England.
"The experience has been fantastic," Haug told Sarpsborg Arbeiderblad as reported by Sky Sports.
"Here they care about real people to thrive, and everything is organised in the best way."
Haug plays for Sarpsborg in Norway, but has attracted interest from several top Premier League clubs including United, rivals City, Arsenal and Roberto Martinez's Everton.
And he confirmed he intends to complete trials with the three other clubs before making a decision on his future.
"We will be with City for three days now and later this year Arsenal awaits and then another stay at Everton where I have been before," he continued.
Arsenal and Manchester United both have a strong track records when it comes to youth development, while City intend to invest heavily in training ground and academy facilities in the next few years.