India's Tata Steel is due on Monday to begin the formal sale process for its loss-making British units which employ 15,000 people, a source close to the company said.

Tata, one of the world’s biggest steelmakers, said on March 30th it was putting its British assets up for sale, citing a global oversupply of steel, high costs, weak domestic demand and a volatile currency.

A source close to the company said a formal announcement would be made later on Monday. Sajid Javid, Britain’s business minister, said on Friday the formal sale process would begin by Monday and that Tata had not set a time frame for the sale.

British Prime Minister David Cameron, already grappling with rows over Europe, his budget and his tax affairs, is trying to find a buyer for Tata's assets.

Britain’s eurosceptic media have blamed Brussels for preventing London from taking greater steps to protect the industry while the opposition Labour Party has called on Cameron to do more to save the plants.

Sanjeev Gupta, the boss of metals trader Liberty House Group who wants to buy Tata Steel Ltd’s British operations, told Reuters on Friday that he has the financial resources to match his ambitions.

Hitting back at critics who have questioned his capacity to take on a business dragged down by heavy debt and weak sales, the 44-year-old Cambridge graduate said he was serious about making an offer and had the backing of a group with $7 billion of revenues.

Reuters