The Information Commissioner’s Office has confirmed it will look into the private use of WhatsApp and other phone messaging apps and channels to conduct government business as well as emails, after Labour asked for more details of its investigation into Lord Bethell, the health minister.

Labour wrote to Elizabeth Denham, the information commissioner, after it emerged Bethell replaced his mobile phone before it could be searched for information relevant to GBP85m of Covid test deals that are subject to a legal challenge.

After the revelation, the party’s deputy leader, Angela Rayner, wrote to the ICO, asking it to confirm that the minister’s use of WhatsApp would be covered by an inquiry into the use of private communications for government business at the Department of Health and Social Care.

In a reply to Rayner, the Information Commissioner’s Office said its investigation “includes messenger apps such as WhatsApp and any other private channels that fall outside of the DHSC’s corporate systems”.

“This includes looking at the retention, security and deletion of matters relevant to the corporate record to ensure that these have been handled appropriately,” it said.

Rayner also called on Simon Case, the cabinet secretary, to make sure every effort is made to retrieve any messages relevant to the judicial review and for assurances that Bethell has complied with the ministerial code.

Bethell, who oversaw the award of Covid contracts, is one of those under scrutiny over the way deals for personal protective equipment (PPE) and tests were allocated at the height of the pandemic.

As part of legal proceedings issued by the Good Law Project, the government is expected to disclose his correspondence including by email, WhatsApp and SMS relating to the award of GBP85m of contracts for antibody tests to Abingdon Health.

However, a witness statement from a government lawyer revealed Bethell replaced his phone in early 2021 and it may no longer be possible to retrieve the information about his dealings with Abingdon, although efforts are being made to recover any messages from his mobile phone provider.

Rayner, Labour’s deputy leader and shadow chancellor of the duchy of Lancaster, said: “Discussing millions of pounds of taxpayer-funded contracts on a private device is unacceptable … Every effort needs to be made to retrieve them from the minister’s phone so that they can be presented in court and included in the pandemic public inquiry.

“These missing messages are vital evidence and bereaved families deserve nothing less than the whole truth.”

In a witness statement, a lawyer for the government said efforts were being made to retrieve any messages from the old phone’s network provider that might relate to Abingdon Health deals.

Abingdon Health said it could confirm no member of its senior management had sent or received texts or WhatsApp messages with Lord Bethell or any other government ministers.

“The mobile phones of the senior management team at Abingdon Health have not been replaced or lost and the senior management team are happy to confirm in sworn evidence that no such text or WhatsApp messages were sent or received,” it said.

The company said Abingdon Health had longstanding expertise in the area of lateral flow test development and said the government had substantially refused to pay Abingdon Health for the goods and services provided under the contract.

It said the company has outstanding invoices with the DHSC totalling GBP6.7m, including GBP5.15m for 1m AbC-19TM rapid tests, which were delivered in early January 2021 and some of which were deployed in the UK Biobank study.