MPs have been told not to name a Conservative parliamentary aide who was arrested on suspicion of spying for China.

Commons Speaker Sir Lindsay Hoyle said commenting on the identity of the researcher could pose a "serious risk of prejudicing any future prosecutions". 

He issued the warning amid speculation the man, reported to be in his 20s and from Scotland, could be named by MPs on the floor of the House today.

Sir Lindsay told MPs that vetting procedures were in place and that "security is working closely and effectively with other relevant authorities".

The researcher, who went to George Watson's School in Edinburgh and also studied at university in Scotland, was arrested in the capital on March 13.

Some MPs were angry that they had not been informed of the arrest at the time and only found out about it in a report in the Sunday Times at the weekend.

“As you know, we do not discuss details of security issues on the floor of the House for reasons which are well understood," said Sir Lindsay in a statement to the Commons this afternoon. 

“This is an ongoing, sensitive investigation and members will of course understand that public discussion will be wholly inappropriate.

“However, I want to reassure members that the House follows the same vetting procedures as the Government, that issues raised by media stories are being addressed and that the security is working closely and effectively with other relevant authorities.We keep our security arrangements under review at all times in order to deal with the evolving threats."

He added: “The extremely small number of people who needed to know were immediately briefed on a strictly confidential basis given the national security of this sensitive matter.”

Sir Lindsay told MPs: “At this stage I do not wish to say anything further about this issue and I would remind all members of the importance of not discussing security issues on the floor of the House.

“That is particularly important in this case, where commenting on the identities of those alleged to be involved, engaging in speculation about the case or discussing other details runs a serious risk of prejudicing any future prosecutions – which the comments made in the media were unhelpful – something for which I’m sure no member will want to be responsible.”

The Commons Speaker said he would not take points of order from MPs on the matter, adding they should raise security concerns with him or officials outside the chamber.
Earlier today the parliamentary researcher, who had links to Conservative politicians, insisted he is "completely innocent".

He said he had spent his career highlighting the "challenge and threats presented by the Chinese Communist Party".

The arrest under the Official Secrets Act led to the Prime Minister confronting Chinese premier Li Qiang at the G20 summit in India on Sunday over "unacceptable" interference in democracy.

In a statement released through his lawyers, the researcher - who has not been officially named by police - said: "I feel forced to respond to the media accusations that I am a 'Chinese spy'.

"It is wrong that I should be obliged to make any form of public comment on the misreporting that has taken place.

"However, given what has been reported, it is vital that it is known that I am completely innocent. I have spent my career to date trying to educate others about the challenge and threats presented by the Chinese Communist Party."