Mumbai, April 8 (IANS): Britain's Serious Fraud Office has opened a criminal investigation into Tata Steel's UK operations, which the company is looking to sell, according to reports appearing in the British media.

The Daily Telegraph reported on Thursday that authorities have launched a criminal investigation into charges that Tata Steel staff, at its Yorkshire's site, may have tampered with certificates on the composition of steel products before its sale.

At least nine employees have been suspended and around 500 clients, including Rolls-Royce and BAE, are affected, the paper said citing sources.

Having suffered nearly 3 billion dollars in losses on the British operations, Tata Steel last week said it will explore the options to put its entire portfolio there up for sale, some 10 years after it forayed into Europe by acquiring the Anglo-Dutch Corus for over 8.1 billion dollars.

The company said the move was to cut its heavy losses from high manufacturing costs, competition with China and a global steel glut. 

Former chairman Ratan Tata has described the UK steel operations as "underinvested and overmanned".

British Business Secretary Sajid Javid flew into this city earlier this week to specifically hold talks with the Tata Group top brass led by chairman Cyrus Mistry, in a bid to avert over 40,000 job losses at Tata Steel UK.

The Tata Group on Wednesday sought the British government's help in finding a suitable buyer for its floundering steel assets in Britain, while also exploring the possibility of a third-party independent auditor to oversee the transition, sources here said.

Speaking to reporters here following the meeting, Javid called it "constructive and positive" and said the Tata Group was a "responsible company". He added that it had told him that a "reasonable amount of time" would be allowed for the sale process.

Javid also tweeted that Tata Steel will begin the formal process to sell its UK units by coming Monday.

Among the parties that have shown interest in purchasing the Tata assets, the British business secretary only named Liberty Steel.

India-born, London-based businessman Sanjiv Kumar Gupta, founder of the UK-based Liberty House, is touted as a strong contender to take over Tata Steel's British assets. He was one of the potential buyers Javid met in London before flying out to Mumbai.

Earlier, British Prime Minister David Cameron held emergency talks in London with his colleagues to tackle the crisis, amid warnings that the firm has just weeks for a rescue deal.

The Labour Party has termed it a national crisis and wants the UK steel industry to be nationalised.