Ministers should be banned from political lobbying for up to five years after leaving office, the anti-corruption watchdog has recommended.

The Committee on Standards in Public Life has published its interim review of lobbying guidelines in the wake of the Greensill affair involving David Cameron.

A number of inquiries have been launched after it was revealed that the former prime minister texted Chancellor Rishi Sunak on behalf of Greensill Capital, a finance firm which employed him as a lobbyist.

Mr Cameron also sent WhatsApp messages to Health Secretary Matt Hancock and other ministers over getting Greensill access to a COVID-19 loan scheme.

The findings said: “Government departments and ACOBA (Advisory Committee on Business Appointments) should be able to issue a lobbying ban for a longer period of up to five years where they deem it appropriate.

“Whether or not a longer ban is warranted will depend on the nature of the position held by an applicant in government.

“If an applicant had a particularly senior role, or where contacts made or privileged information received will remain relevant after two years, a longer ban may be necessary to ensure that former officials lobbying government are not directly benefiting from their time in office when they do so.”

The committee’s final report and recommendations will be sent to the prime minister later this year.