Spy chiefs believe the scale of Russian and Chinese influence on Parliament is now a major threat to national security and have drawn up a secret watchlist of lords with dubious connections.

It is understood that more than a dozen are feared to have been compromised by financial interests with foreign powers – with MPs today demanding a tough crackdown.

However, security sources add that concerns within MI5 and the Home Office go beyond commercial ties, with other members of the Upper House suspected of being cultivated by enemy agents. Concern has soared as diplomatic relations between London and Moscow have plunged in the wake of the Salisbury nerve agent outrage.

Spy chiefs have drawn up a secret watchlist of lords with dubious connections to Russia or China

The stark warning raised at the highest levels in Whitehall comes as an investigation by The Mail on Sunday reveals 30 members of the House of Lords have direct financial links to Russia or China.

Among them are peers with board memberships on Moscow-owned firms or positions with Chinese companies. They include a Russian expert who has written books about the country and executives of Russian banks, mining firms and state-backed shipping conglomerates.

Others, not named for legal reasons, have publicly attacked sanctions against Russia in the Lords chamber and used written parliamentary questions to probe Government foreign policy stances while working for Russian firms.

Comments made in the Lords have also been published online by RT – the controversial Russian news channel slammed by Ofcom this week for its pro-Kremlin bias.

An investigation by The Mail on Sunday reveals 30 members of the House of Lords have direct financial links to Russia or China and spy chiefs believe the scale of their influence on Parliament is now a major threat to national security

Last night Tory MP Bob Seely called for the rules for peers to be tightened by a ‘Foreign Agents Act’.

He argued for the equivalent of the US Foreign Agents Registration Act – which ‘was designed to block not only foreign powers but also powerful foreign individuals or companies covertly or discreetly influencing US democracy’ – to be introduced in the UK.

Mr Seely told The Mail on Sunday: ‘If you want to work for Russian President Vladimir Putin or his cronies, directly or via proxies, you need to be open and honest about it, describe the work you do and who you meet and why.’