Ousmane Dembele
Ousmane Dembele joined Dortmund during the last summer transfer window. Getty

Borussia Dortmund's director of football, Michael Zorc, has told Barcelona to forget about signing Ousmane Dembele. The club chief even threatened to take legal action following reports the Catalans have reached an agreement with the France starlet to lure him to the Nou Camp ahead of the 2017-18 season.

Barcelona tried to sign Dembele from Rennes during last summer's transfer window. However, the 20-year-old decided to move to Dortmund instead as he didn't want to be a mere back-up for Lionel Messi, Luis Suarez and Neymar.

The Catalans have reportedly decided to resurrect their interest in the Frenchman amid suggestions new manager Ernesto Valverde wants a pacy winger to play on the right flank in order to use Messi in a deeper role.

The Frenchman has apparently been convinced by the Barcelona officials to cover that role following a sensation debut campaign with the Bundesliga giants, scoring 10 goals and providing 21 assists in 49 appearances.

Bild reported over the weekend that Barcelona technical secretary Robert Fernandez had met Dembele's agent Moussa Sissoko to discuss the winger's move to the Nou Camp.

And on Thursday morning Sport provided a major development in the saga, claimingBarcelona have already agreed a five-year-deal with the player ahead of completing the move.

The Spanish publication added that Barcelona were confident in convincing Dortmund to cash in on with the winger with an offer worth €50m (£44m, $55.8m) plus €20m in add-ons.

However, Dortmund director of football has now warned Barcelona that Dembele is not for sale at any price – even though they only paid €15m to secure his services last summer.

"Ousmane Dembele has a long-term contract. There are no negotiations," Zorc said as quoted by WAZ. "Dembele will play for BVB in the coming season. If Dortmund is not contacted [by interested clubs], we could initiate a FIFA procedure."