Damien Comolli, Tottenham Hotspur's sporting director, has warned Manchester United that Dimitar Berbatov will not be sold for any price during the January transfer window.

Sir Alex Ferguson is a long-term admirer of Berbatov, and although he has stated he is happy at Tottenham the Bulgaria striker has been linked with a move to Old Trafford.

"We have never had any talks with Manchester United - and as Juande Ramos has stated, we want him to stay," Comolli said. "It's not an issue. I don't think there is a price for him."

Tottenham also want Jermain Defoe to sign a new contract to avoid losing him for free at the end of next season. "We want him to stay, and he wants to stay - when two parties want to succeed there is usually an agreement," Comolli said. "It's a good sign."

Comolli was in Switzerland where Tottenham were drawn against Slavia Prague in the last 32 of the Uefa Cup, but he remains wary of the Czech side, despite their 7-0 thrashing by Arsenal earlier this season.

"We played them last year in the Uefa Cup and know how difficult it was - it was tough, especially over there," he said. "I think they just had a bad day at the Emirates. They also drew against Arsenal at home and that is what I will be keeping in mind.

"We were very disappointed last year, because we thought we could beat Seville in the quarter-final - and we are very ambitious."