Baroness Mone and her husband Doug Barrowman have described the Covid inquiry as a “politically-motivated witch hunt” that denies them the right to defend themselves against accusations over the supply of medical equipment.

The inquiry’s chairwoman Baroness Hallett, who rejected their first application last month, denied their second attempt to be treated as “core participants”, saying it had been made “significantly out of time”.

PPE Medpro, a firm led by Mr Barrowman, was awarded government contracts worth more than £200m after Baroness Mone recommended it to ministers.

The couple wanted access to inquiry documents, and the opportunity to make statements and question witnesses.

Baroness Hallett did not accept they had a large enough role “in the matters to be investigated by the inquiry”.

The Covid inquiry is looking into £15bn of PPE deals during the pandemic. The National Crime Agency (NCA) has been investigating the company since May 2021 over suspected criminal offences committed in the procurement process.

No charges have been brought and the Crown Prosecution Service has not been instructed in the case. Baroness Mone, 52, and Mr Barrowman, 59, have both denied wrongdoing.

The inquiry will publish evidence presented in a closed session once restrictions are lifted.

In a joint statement, Baroness Mone and her husband said the decision to hear evidence in private was “a blatant betrayal of transparency and justice” and accused the NCA of waging “a ruthless campaign” against them.

The couple added: “While the inquiry refused to exclude PPE Medpro, it handed the NCA the power to dictate the proceedings behind a wall of secrecy, ensuring that only their version of events is heard – while we are denied the right to defend ourselves.”