NEW documentary evidence about a pregnancy test drug linked to thousands of birth defects bolsters claims of an alleged cover-up, says a Bolton MP.

Hundreds of files relating to Primodos, a hormone test prescribed to expectant mothers in the 1960s and 1970s, were uncovered by Sky News at the Berlin National Archive, in Germany, last year.

Among them were findings in January 1975 by the UK’s then principal medical officer that women who took a hormone pregnancy test had a “five-to-one risk” of having a child with birth defects.

The test has been officially linked to more than 3,500 women whose babies suffered birth defects, but campaigners believe it could be far higher.

Sky News said Dr William Inman, of the Committee on Safety of Medicines, reportedly wrote to the drug’s manufacturer Schering, and warned them to “take measures to avoid medico-legal problems” and later that he had destroyed his research to avoid “individual claims” being made.

Meanwhile, a letter from Dr Inman published in the British Medical Journal in April of the same year shows the committee had “through its spontaneous reporting scheme only a small number of reports alleging a possible causal association between ‘the use of drugs during pregnancy and the subsequent delivery of a malformed child”.

His letter concluded the “preliminary” findings of his research meant there was “little justification” for the ongoing use of such tests.

The medical regulator was first notified about the potential link in 1967, but did not issue any warning until June 1975.

Bolton South East MP Yasmin Qureshi said an all-party parliamentary group had identified hundreds of potential victims but she believed there could be many more.

“This is only the tip of the iceberg,” she said.

“I think there’s thousands out there who have disabilities as a result of this drug.

“Initially, from what I saw, the Committee on Safety of Medicines seems to have known this drug was causing problems but did nothing, completely nothing.

“It was years and years later before they said it should come off the market.”

The Government set up an independent inquiry to look into Primodos in 2014.

Pharmaceutical giant Bayer, which acquired Schering Healthcare in 2006, maintains there was “no link” between Primodos and birth defects.