Agent Mino Raiola has warned Real Madrid and Barcelona not to miss out on signing Erling Haaland, and said the forward could be on the move this summer despite Borussia Dortmund's reluctance to agree a transfer.

Raiola made high-profile visits to Madrid and Barcelona last month for talks with both clubs, accompanied by Haaland's father Alf-Inge.

- Karlsen: The very best players aged under 21
- Connelly: Transfer dominoes set to fall this summer

Dortmund sporting director Michael Zorc has said that Haaland -- who has 21 Bundesliga goals this season as well as scoring 10 in eight Champions League games -- won't be leaving the club at the end of this season.

"What we know today is that Dortmund spoke seriously with us and told us 'we aren't selling him,'" Raiola told AS in an interview on Saturday. "Now we'll have to see if that's their wish until Sept. 1... That's Dortmund's official position. But I have another position, I think that if a good opportunity comes up and everyone is happy, we'll put it on the table."

Dortmund are fifth in the Bundesliga, a point off the Champions League qualification places.

A release clause in Haaland's contract doesn't come into effect until 2022, and sources told ESPN that there is no provision in his deal to trigger a departure if they miss out on Champions League football next season.

"Haaland is interested in two things: scoring goals and winning trophies," Raiola said. "When a club like Barcelona or Madrid comes along, with so much history, it's hard to say no. Paris Saint-Germain are joining that group of big clubs, [Manchester] City are trying to, Juventus always have been. The league they play in is important too."

Sources told ESPN that Raiola's meeting with Barcelona on April 1 was a first step towards exploring the possibility of his signing, while talks with Real Madrid were "friendly" and "like those we often hold regarding players."

The financial situations of both La Liga clubs would make a deal for Haaland difficult.

ESPN has reported that Barca are now looking for new ways of bringing in funds after the collapse of the proposed European Super League, which would have landed them an additional €350 million.

"I don't know if Real Madrid could afford Haaland," Raiola said. "I haven't studied their finances. But I think so. The question is a different one: can Madrid afford not to buy Haaland?"

He described Barcelona's prospects of landing the 20-year-old as "complicated but not impossible" saying: "It's the same for clubs and players: a train goes past and you catch it or you don't."

Raiola also discussed the future of another client, Manchester United midfielder Paul Pogba, who has been frequently linked with Real Madrid.

"Playing at Madrid was always attractive for him because of Zidane, he was his idol," he said. "Nothing is impossible, but football depends on the day. You have to be flexible. What if tomorrow, Madrid want to swap [Eden Hazard] for Pogba? That's just an example, but if all four parties want to, why not?"