Tata Motors’ tie-up with MG Rover Group Ltd was under strain and might lead to a break-up as the British company is planning to forge an alliance with a Chinese firm, Tata Motors Chairman Ratan N. Tata has warned.“I would say that if their engagement is really a full-fledged engagement, then I have no doubt that we will move to a second or third level of involvement, which is tantamount to saying there is no engagement at all,” Tata told the London-based Sunday Times.Sales of Tata’s cars in UK were not on expected lines. It sold only 6,000 units as of now as against anticipated sales of 30,000 units.The two companies had entered into a tie-up to sell Tata’s compact car Indica in the British and other European markets as City Rover. Rover is now planning a similar deal with Shanghai Automotive Industry Corp (SAIC), a major player in the Chinese market. “To be very frank, we do not know what the extent is of their engagement with SAIC. They have been less than forthcoming themselves,” Tata said.Tata officials confirmed that Indica was sold to MG Rover for just 3,500 pounds despite the City Rover being priced at about 6,495 pounds to 8,895 pounds in the British market.