UK's Serious Fraud Office has initiated a criminal investigation into Tata Steel's operations, the Telegraph reported on Thursday.
Police officers are investigating charges that Tata Steel's staff in and around its Yorkshire's site, may have faked certificates on the composition of the products before its sale, the newspaper said.
Examined documents have affected 500 customers, including BAE and Rolls-Royce, Telegraph said, citing a source.
Tata, the biggest steel producer in Britain, has put its British businesses up for sale due to high costs, weak demand and a flood of cheap supplies from top producer China.
The British government, under fire for the way it has responded to the crisis, opened talks with potential buyers for Tata Steel's UK operations, including Gupta's Liberty House, earlier this week.