Tottenham were at the centre of two of the biggest potential transfer deals of the summer last night with talks under way for David Bentley to join from Blackburn Rovers for a deal worth up to £17m. At the same time, Manchester United, whose chief executive, David Gill, has returned from holiday to take care of transfer business, were informed that they need to bid closer to £30m to sign the Spurs striker Dimitar Berbatov.

Bentley, who was pulled out of Blackburn's 2-1 friendly win at Macclesfield last night with a calf strain, has made no secret of his desire to move on, and has refused to sign a new contract. Blackburn have been examining replacements should Spurs, who are the only serious bidders after Aston Villa offered just £10m, meet their valuation. "We have had an offer from Aston Villa, but I do not want him to go," said Paul Ince, Blackburn's manager, last night.

Discussions are believed to have taken place yesterday between the Spurs chairman, Daniel Levy, and Blackburn's chief executive, John Williams, with a variety of options being examined. Spurs are reluctant to meet Blackburn's valuation for the 23-year-old England international, but would be keen to do a deal if the price can be reduced by the inclusion of a player. The obvious candidate is the goalkeeper Paul Robinson, who has been replaced as Spurs' No 1 by the Brazilian Heurelho Gomes and can leave the club, but there is a discrepancy over his valuation. Matters are also complicated because the future of Blackburn's goalkeeper Brad Friedel, who has attracted bids from Manchester City and Villa, has not been decided.

"When I came to Blackburn, I said I wanted to keep my best players, and Brad Friedel comes into that category," said Ince. "I do not want to sell Brad, so why should I want Paul Robinson?"

There are other players Spurs are willing to sell and, given that Blackburn are in the market for a specialist right-back, that may lead to Pascal Chimbonda also being offered to them. But Blackburn, who head to their training camp in Germany tomorrow, have said they would rather have cash for Bentley, especially as they want to fund a deal for Jermaine Pennant from Liverpool.

Pennant has been told by his manager, Rafael Benitez, that he can leave and is happy to move to Ewood Park. But Liverpool want £6m for the 25-year-old while Blackburn, whose game against Macclesfield was their first under new manager Ince, are prepared to pay no more than £4m at present.

A further complication for Blackburn is the future of Roque Santa Cruz. Yesterday the Paraguayan admitted he was "motivated" by the interest shown in him by other clubs after scoring 23 goals last season, his first in the Premier League. However, he said he was happy to remain at Blackburn if no bids were accepted for him.

It is unlikely that Blackburn, given they are preparing for their first season under a new manager after Mark Hughes' departure, would want to sell Bentley and Santa Cruz in the same summer. Manchester United have been one of the potential suitors for the former Bayern Munich striker, along with Arsenal and Spurs, but now appear set to rekindle their interest in Berbatov after a bid for the striker was rejected last summer.

Berbatov has been clear with Spurs that he would prefer to leave after two seasons – he even made that request just months after joining from Bayer Leverkusen for £11m – and although Levy would prefer to sell him abroad the only concrete offer is about to come from United.

An initial inquiry of £20m is understood to have been rebuffed. And although Spurs said they would not lower their valuation of £30m, a compromise may well be about to be reached of around £28m which would include a number of add-ons.

Levy and Spurs are, however, sensitive to the fact that their supporters would react badly to Berbatov's sale if it took place before reinforcements were signed. A £9.5m deal for the Espanyol striker Luis Garcia has been discussed by Tottenham, although that may not go ahead if Bentley is signed, while Spurs will want to hold on to their striker Robbie Keane, who is the subject of a bid from Liverpool, should Berbatov be sold. Darren Bent may also be retained.