Lord Drayson, centre, has declined to respond to allegations
A BBC investigation has uncovered concerns about the quality of TB vaccines produced by a factory once owned by junior minister Lord Drayson.
The Money Programme says understrength drugs were produced at a factory bought by the peer's Powderject firm in 2000.
Reporter John Sweeney said this raised fears some inoculated British children were not protected from TB.
Lord Drayson declined to comment. The Department of Health does not believe vaccines were "significantly impaired".
The Money Programme said official documents show that from 1989 some of the TB vaccines manufactured at the factory were faulty.
Powderject bought the factory, in Speke, Liverpool in 2000, but "kept quiet" for 21 months and did not tell health regulators that some batches were understrength.
The documents, from the Medicines Control Agency (now the Medicine and Healthcare product Regulatory Authority), were obtained under the Freedom of Information Act.
"There is no evidence that failing stability (potency) result have been reported to the Medicines Control Agency," the document said.
It was only when health inspectors staged a crash inspection in July 2002 that Whitehall - not the public - was informed.
The Department of Health says the chance of vaccines being significantly impaired is "unlikely".
Lord Drayson, a junior defence minister who has donated thousands of pounds to the Labour party, has been made aware of the investigation's findings but has not responded.
He sold the factory in 2003 and was made a life peer in 2004.
Dr John Moore-Gillon from the UK charity TB Alert said it was "very unlikely that anyone's come to any material harm".
"They're very likely to have received adequate protection and I don't think that anyone's going to be unprotected.
"Having said that, we do need to look to the future and check that the highest possible standards are adhered when vaccines, like TB vaccines, are made," Dr Moore-Gillon said.
The Irresistible Rise of Tony's Crony: A Money Programme Special, is screened on BBC Two at 10pm on Monday, 21 November.