Fulham last night slapped a prohibitive £18m price tag on the head of Louis Saha as Chelsea joined Manchester United in the chase for the French forward.

The Cottagers insist reports their star striker is poised to join United for £9.8m are without foundation.

And the transfer saga stepped up yesterday when Fulham sources said their west London rivals Chelsea have now ''expressed an interest'' in Saha.

No ''serious negotiations'' have taken place with the Blues and nor has Saha been given permission to talk to any club.

However, Mohamed Al Fayed's club rate the 25-year-old's value at £18m - almost a tenfold increase on the £2.1m they paid Metz for him four years ago.

And, even for Chelsea, that would represent an enormous outlay and a transfer record, eclipsing the £17m paid to Blackburn for Damien Duff in the summer.

Fulham are aware their valuation must be negotiable if they choose to sell Saha.

But they insist United's £8m fee, rejected last week, and even a genuine £9.8m offer, would be too low.

Saha struggled for two seasons, mustering a total of just 13 league goals, before hitting a purple patch and equalling that tally in just half of this campaign.

That is the reason for Fulham's expensive valuation as United and Chelsea mull over their options with a fortnight of the winter transfer window remaining.

Blues boss Claudio Ranieri has been linked with a multitude of striker signings this month.

But his club's approach for Saha coincides with Tuesday's news that Hernan Crespo will be out until March with his calf injury.

It is understood that, while United boss Sir Alex Ferguson remains interested in bringing the striker to Old Trafford, no deal is imminent, even though Saha was quoted yesterday as saying he is ''very happy'' that the transfer has gone through.

A Fulham spokesman said: ''There has been no fresh bid from Manchester United. There is no truth in the story at all.''

United insiders believe Fulham are trying to establish Saha's market value, even though Cottagers boss Chris Coleman does not want to lose the player.

Even if a deal with United were rushed through this week, Saha would not be considered for Saturday's Premiership match with Wolves and he is also ineligible for the FA Cup tie at Northampton the following Sunday.

Saha's departure looks inevitable after he evoked memories of Paul Ince's acrimonious departure from West Ham in 1989 by speaking out about his intended move.

Ince famously posed in a Manchester United shirt while he was still a West Ham player, so determined was he to join the Red Devils. A problem with his medical raised the unfortunate possibility of Ince being forced to stay at Upton Park, until a pay-as-you-play deal was eventually agreed, but even now the veteran Wolves star is bombarded with abuse whenever he faces the Hammers.

''I have wanted to go to United in my mind for a month and now I know that I must prove I can play there,'' said Saha. This is a big step up in my career and I know I will have to show I am good enough.''

Ferguson seems certain to concentrate his energies on bringing Saha to the club and ditch the idea of trying to recruit Leeds striker Mark Viduka, who is currently in Australia visiting his father who is seriously ill. However, with Chelsea on the horizon the emphasis could switch from Manchester to London and Stamford Bridge.

* Chelsea manager Claudio Ranieri yesterday insisted Joe Cole is not for sale.

Ranieri, reacting to press reports linking Cole with a swap deal involving Charlton's Scott Parker, made it clear he has no intention of allowing his England midfielder to leave Stamford Bridge.

Cole has had to battle to keep his place in the big-spending Blues' squad this season, as Ranieri has rung the changes in his bid to stay in the race for the Barclaycard Premiership title.

But Ranieri said: ''Joe is a highly valued member of Chelsea's first team squad.

"He is playing an important role in our exciting season.''