The leader of the House of Lords has been urged to back calls for tighter restrictions on peers being paid to offer political advice after a Guardian investigation found one in 10 have held such roles.

Gabe Winn, chief executive of Blakeney, a lobbying firm, wrote to Angela Smith on Tuesday, saying he and many others in the industry believed the issue was “bringing the work of the House of Lords into disrepute”.

He called on her to make the issue an “urgent priority” after the Commons introduced changes to ban all paid advocacy by MPs from October last year.

Conduct in the House of Lords is overseen by the conduct committee, chaired by a cross-bench peer, Eliza Manningham Buller. The committee is bringing in a revised code next month, but it will not tighten the rules that allow peers to give political or policy advice for payment.

Analysis by the Guardian showed this week that more than one in 10 peers have taken payments from businesses such as lobbyists and companies operating in the banking, defence and energy sectors. Peers can earn tens of thousands of pounds a year for such roles.

In his letter to Smith, copying in the Lords standards commissioner and Pat McFadden, the most senior Cabinet Office minister, Winn said: “I am writing to bring to your attention an issue that I and many others in my industry believe is bringing the work of the House of Lords into disrepute: the issue of peers who are paid by lobbying firms … I firmly believe that lobbying is an essential part of the parliamentary process and that, done ethically and transparently, it helps make better laws by bringing together the right facts, research, insights, and arguments to inform policymakers.

“However, I and other leaders in my industry have become increasingly concerned at the growing perception that lobbying lacks the transparency and trust that are essential to the integrity of our democratic system.

“This has been true in both houses of parliament. But, whilst the leader of the House of Commons introduced changes to the exemptions on paid advocacy roles for MPs from 25 October 2024, the equivalent has not yet been done for members of the House of Lords.”

He highlighted that Lucy Powell, the leader of the House of Commons, helped drive through reforms to the MPs’ code of conduct, saying “loopholes” that existed could allow an MP to “use their privileged position and knowledge for personal gain”.

Winn said: “Although I recognise that the role of members of the House of Lords differs to that of MPs, the issues raised by Lucy Powell are equally applicable to both houses. Members of the Lords play a significant role in the making of legislation in this country, participating in debates, committees, and wider parliamentary life, all of which provides them with privileged information and access.

“The fact that a member of the House of Lords is now seen as a lucrative addition to some lobbying firms’ armoury is not, in my view, something that we should celebrate.”

The Guardian’s analysis found 91 members of the Lords were being paid for their political advice by organisations such as Santander bank, the French arms manufacturer Thales and the British digger manufacturer JCB.

Peers are valued for their experience, and the House of Lords rules take into account that many continue to work alongside their role in the upper chamber. Unlike MPs, peers are not paid a salary. However, they are entitled to a daily tax-free allowance of £361.

Under these rules, peers can take paid consultancies to give general advice on political issues, current affairs and how parliament works. To prevent commercial concerns from getting an unfair advantage, peers are not allowed to use their political position to lobby directly for an individual company or business that is paying them.

This means they cannot contact ministers or officials to promote that company. Nor can they, for example, draw on their political experience to tell the business which official to approach if that company wanted to advocate for its commercial interests.