By Philip O'Connor

STOCKHOLM, May 30 (Reuters) - Norway striker Erling Haaland smiled broadly but remained tight-lipped about his move from Borussia Dortmund to Manchester City as he joined up with the national squad for their four Nations League matches next month.

The 21-year-old, postingnews who scored 22 goals in 24 Bundesliga games in the past season will become a City player on July 1, entered Monday's news conference in Oslo rubbing his hands, but he had little enthusiasm for discussing his club situation.

"(The last few months) have been tough. This thing, it hasn't been simple, at the same time I have been doing the best that I can for Borussia Dortmund for two and a half years," he told reporters.

"It wasn't easy, but I've done the best I can for the club. I'm ready for four games (with the national team) and that makes me happy," he added.

Norway manager Stale Solbakken opened the conference by pointing out that Haaland had not been presented by his new club yet, and that the player would not be answering questions about his future there.

City chairman Khaldoon Al Mubarak did not mince his words, however, saying the Premier League champions had invested in the "best number nine in the world at the right age.

"Haaland, from his early days in Norway and then moving on to Dortmund, has been on our radar for at least four or five years," he said in an interview website on City's website.

"He is a very, very unique, incredibly talented striker that I think the whole world has been looking at.

I would say every big team in the world wanted (him) to join and we're absolutely delighted that Haaland chose to join Manchester City."

Haaland also described his pain at the death of his agent, Mino Raiola, on April 30, 10 days before City and Dortmund announced that an agreement had been reached for his transfer.

"It made things different.

You can imagine, I don't have to say too much more," Haaland said. "But that's how it is. I can't complain, I like my life, I like where I am. I shouldn't complain."

Haaland explained that he overcame the pressure of months of speculation about his club future by concentrating on what he could control.

"If I can boast a little, if there's something I'm very good at it's focusing, focusing on football and not on things I shouldn't focus on, shutting out everything," he said.

Norway play Serbia and Sweden away on June 2 and June 5 before returning to Oslo to host Slovenia and the Swedes in Nations League Group B4.

(Reporting by Philip O'Connor, Additional reporting by Rohith Nair; Editing by Christian Radnedge and Ken Ferris)