After emerging as the top bidder for Ford's brands, the Indian carmaker has assigned its financial advisors Citigroup and JP Morgan to arrange the funding with a range of other international and domestic banks.

The loan is larger than anticipated, as the purchase of the two carmakers has been estimated to be worth around $2bn.

Tata has not publicised details regarding the additional $1bn but sources familiar with the deal said it could be used for working capital for the carmaker.

The current period is a tough time for acquisition financing, as companies face higher prices in raising high-yield bonds for takeovers.