Workers' leaders last night called on Ford to state its intent after it hired investment bankers to oversee a potential sale of Jaguar and Land Rover.
The American carmaker is said to have handed Goldman Sachs, Morgan Stanley and HSBC a mandate to sell the two luxury car businesses which could fetch up to £5 billion.
The move came amid mounting rumours over Ford's plans for its Premier Automotive Group brands as it steps up a group-wide restructure designed to halt record losses.
Ford sold Aston Martin for £450 million in March and there has been increasing speculation over a possible sale of Jaguar after the overall group revealed that losses widened to $12.7 billion (£6.5 billion) last year - the largest deficit in its 103-year history.
Ford last night would not comment on any potential sale of the companies which employ nearly 15,000 in the Midlands.
A Ford spokesman said: "This is only speculation and something we cannot confirm or deny.
"We have said we are assessing all of our operations, as every good business does."
Goldman Sachs, Morgan Stanley and HSBC also declined to comment.
But Dave Osborne, national secretary for the car industry at the T&G section of Unite, called on Ford to reveal its intentions.
He said: "We would find it difficult to understand why Ford would want to sell a successful, growing and environmentally improving brand like Land Rover and a marque like Jaguar which is a significant player in the luxury market and one that Ford has invested heavily in.
"There have been persistent rumours and spec-ulation which we have pressed Jaguar and Land Rover to deal with as our prime concern is the job security of our members.
"We should not need the spectre of people like Alchemy, whose down-sizing reputation goes before them, to provide the answers we require."
The speculation was sparked after Jon Moulton of private equity firm Alchemy was reported to have expressed interest in buying the two carmakers in a £3 billion deal.
Mr Moulton, who tried to buy MG Rover from BMW in 2000, said he was interested in the two companies which have enjoyed different fortunes under Ford's PAG.
While Land Rover has achieved record sales in the last two years, Jaguar has continued to struggle with falling sales.
In the year to date, Land Rover's UK sales were 3.19 per cent ahead of last year at 20,489 vehicles, while Jaguar was 16.8 per cent down at 8,667.
In one report, Mr Moulton said he was apparently interested in the two marques and turning them into niche manufacturers.
He said: "I am very interested in a bid for Land Rover and Jaguar in particular. These two marques come together because they share similar platforms. The quality of the product has improved in recent years. What is needed now is to produce lower volumes of the cars to make the business a success." Mr Moulton was said to believe £3 billion is a realistic offer for the two famous names, but noted that some observers feel Ford will not accept less than £4 billion.
However, Alchemy later retreated from the speculation. A spokeswoman said: "We are interested in these brands at an emotional level, but we have not spoken to anyone and this is not something we are working on."
The PAG pre-tax losses last year rocketed from $89 million (£45 million) in 2005 to $327 million (£166 million).
But in the first quarter of 2007, the division improved its performance to achieve record pretax profits of $402 million (£201 million) compared with $152 million (£76 million) in 2006.
Ford does not break out the results for individual operating units, but industry insiders speculated that Jaguar, a serial loss maker, was making progress in its struggle to return to profit.
It was only in January that Ford chief executive Alan Mulally said: "Jaguar is not for sale at this time. We really like the progress Jaguar is making both on the product side and on their quality and productivity."
The business employs about 10,000 in the UK, at sites in Browns Lane and Whitley in Coventry, Castle Bromwich in Birmingham and Halewood, Liverpool.
Land Rover employs about 9,000 in the UK, with the bulk of the workforce at its manufacturing sites at Lode Lane in Solihull and Halewood, alongside its product engineering centre and head office in Gaydon, Warwickshire.