Millions of people face being barred from receiving covid-19 tests in england because their identity cannot by verified by a credit-checking company contracted by the government to prevent the abuse of the public testing system.

Transunion, a credit-checking company, is used by the department for health to verify the names and addresses of people who request home coronavirus tests. campaigners said that although the company did not run a credit check, the company verifies users identities against databases, such as the electoral roll.

Up to 5.8m people with poor credit histories in the uk could struggle to order the home kits, according to the london assembly, which on tuesday wrote to london mayor sadiq khan highlighting the barriers people may face in accessing tests.

Many londoners have thin credit files because of social and economic disadvantage, and these people are being prevented from accessing home covid-19 tests because of the difficulties they face in verifying their identity with transunion, dr onkar sahota, chair of the london assembly health committee, wrote.

The uk government has been under intense pressure to boost testing capacity after the system was overwhelmed by demand this month as the number of coronavirus cases in britain surged and people experienced covid-19-like symptoms.

The department for health said the verification process, provided by transunion, was used to confirm an individuals name and address which is to reduce fraud and prevent multiple testing kits being ordered, diverting capacity from where it is needed most.

It said those who failed the check would be able to book a test by telephone, or access in-person testing where a member of staff could confirm their identity in person.

However, dr sahota said those unable to verify their identity would be more likely to struggle to use english-language telephone lines, or to safely travel to drive-through clinics which could be located far from their homes.

Londoners cannot be sent hundreds of miles to other parts of the uk to take a covid-19 test or, even worse, left in limbo without access to these much-needed tests, he said.

Claire, a 28-year-old australian citizen who has been living in london for less than a year, said she had tried numerous times a day to register for a coronavirus test to be delivered to her home, but was unable to get past the identity check in the government portal.

As a new migrant i was subletting, all the bills are in my partners name, my bank is an online bank, im not on the electoral roll, she said. with no access to a car, and unable to use public transport without the risk of spreading the virus, she and her partner isolated for 14 days.

It was pretty painful not being able to leave our apartment, she said. it might not have been covid but there was no way of checking, so we had to stay home.

Transunion acknowledged that in some cases it would be unable to verify an individuals identity, which it said could happen for a number of reasons. it did not give any further information about the criteria used to verify the identity of applicants.

While both the department for health and transunion said the processes were necessary to prevent fraud, campaigners cast doubt on the idea that credit-checking companies were required to prevent people ordering multiple tests to sell for profit. theyre really cutting off access for one group to address a problem thats not an issue at all, anna miller, head of campaigns and advocacy officer at doctors of the world, a healthcare charity.

The british medical association, the doctors union, added that the use of credit-checking companies may also discriminate against women, who in some communities are less likely to have records of economic activity, and other vulnerable groups such as undocumented migrants already anxious about how their data may be used.

We are extremely concerned that this heavy-handed and onerous system could be preventing people who need tests, dr john chisholm, bma ethics committee chair, said.