A 46-year-old man has been arrested as part of the National Crime Agency (NCA) investigation into PPE Medpro, the firm linked to Baroness Mone.
The suspect, from Barnet, north London, was held at his home on Wednesday morning.
The NCA is investigating suspected criminal offences in the procurement of PPE contracts by the company.
Mone, 52, and her husband, Doug Barrowman, 59, have faced controversy over the so-called “VIP lane” contracts granted to some suppliers during the coronavirus pandemic.
PPE Medpro, a consortium led by Barrowman, was awarded government contracts worth more than £200 million to supply personal protective equipment after Mone recommended it to ministers.
The Department of Health and Social Care has issued breach-of-contract proceedings over the 2020 deal on the supply