Tata Motors has promised to keep Jaguar and Land Rover’s three UK plants and two product engineering sites open until at least 2011 as part of its winning bid to buy the two carmakers, it emerged on Wednesday.

The Indian group’s pledge appears to have played a decisive role in securing unions’ endorsement of its $2.3bn bid for the two brands, which will see Ford Motor continue to supply them with engines, components and technology, and its credit arm to provide vehicle financing for up to a year.

The purchase marks a new peak for global acquisitions by India’s expansive companies, led by the Tata group, one its oldest and biggest conglomerates.

Bankers believe there will be many more such deals as cash-rich emerging-market companies take advantage of the downturn in the west and a slump in activity by private equity firms to buy up some of their better established but struggling rivals.

Tata’s pledge – at a meeting with unions in London in November – was welcomed in Britain’s West Midlands region as giving breathing space to Jaguar and Land Rover factories that have been regularly tipped for closure.

In a cost-conscious industry where rationalisation and relocation to lower-cost countries are common, the plants produce only about 300,000 vehicles.

Jaguar is losing money, but Land Rover is profitable. Unions succeeded in pressing Tata to pledge broad support for the carmakers’ existing five-year business plan.

Dave Osborne, national secretary for the car industry in Britain’s Unite union said: “Tata has confirmed there will be no changes to the manufacturing and product development footprint under the business plan, which runs up to 2011.”

“That is good news for the employees and the UK economy.”

Tata said: “It is true, as per the business plan agreed between the management of Jaguar and Land Rover and the unions, and it is based on assumptions made in that business plan.”

Aniket Mhadre, analyst with Centrum Broking in Mumbai, said: “In the short term, it’s very negative for Tata Motors, primarily because Jaguar is lossmaking.”

Tata is said to have made no specific commitment to maintain the two brands’ staffing at its current level. However, Ford said it did not “anticipate any significant changes to Jaguar/Land Rover employees’ terms of employment on completion” of the deal, expected by mid-year.