Antoine Griezmann
Griezmann has indicated he has held positive talks with Atletico over a new deal. Getty

Manchester United and Chelsea target Antoine Griezmann has not yet decided to sign a new contract at Atletico Madrid and is listening to offers from other clubs, according to the Frenchman's football advisor.

Griezmann has been integral to Atletico's success over the past three seasons under Diego Simeone and is expected to have a prominent role in Didier Deschamps' France team at this summer's European Championship.

Atlético are looking to reward Griezmann's excellent form with a lucrative new deal and increase his release clause from €80m (£63m, $90.5m) to something closer to €100m. The player recently indicated positive talks are ongoing, but the 24-year-old forward's football advisor Eric Olhats now claims other clubs have made contact.

"Contrary to certain claims announcing that Antoine at Atletico next season will be the case without fail, nothing has been decided or endorsed," Olhats told L'Equipe.

"We are currently listening to different clubs who also offer real interest and attraction."

L'Equipe adds that Manchester United, Chelsea and Paris Saint-Germain are the "serious contenders" for his signature.

Griezmann will feature in Saturday's Champions League final showdown against Real Madrid, a repeat of the 2014 final where Los Blancos won 'La Decima'. Real have also been linked with an ambitious move for the France international, but he insists even a call from his French legend Zinedine Zidane wouldn't convince him to join his club's cross-city rivals.

"If Zidane calls me [and asks me to join Real] I will say that I'm at Atlético," Griezmann said to Canal + France. "Zidane is a great person, but I'm here. I'm even talking to renew my contract. I hope [the talks] will succeed."

Manchester United's reported interest in the Atletico forward is made all the more compelling by the club's imminent appointment of Jose Mourinho, who was linked with a move for the player while manager of Chelsea last summer.