Jaguar and Land Rover employees in the UK were told about the negotiations on Thursday morning shortly before the company made the announcement.
Focused talks
A Tata Motors statement said: "We are now entering a period of more focused and detailed negotiations with Ford.
"We hope both parties can reach an agreement in the forthcoming weeks, though these are complex discussions and there is still much work that needs to be done before that position is reached.
"We are pleased by the progress in the discussions to date and very positive about the prospects of this business going forward."
Ford executives have said they expect to sell the two British automakers early this year.
Jay Ward, a Ford spokesman in London, would not say how much Tata bid for the car manufacturers.
Nor would he say if two other bidders, Mahindra & Mahindra Ltd, another Indian car maker, and One Equity Partners LLC, a US private equity firm, still were in the running.
Last month people close to the negotiations with Ford told the Associated Press news agency that potential suitors had submitted bids for both companies that ranged from $1.5bn to $2bn.
A person briefed on the negotiations said on Thursday that Mahindra and One Equity still were under consideration, although Tata is the likely buyer.