Christopher Cash, 29, the researcher, and Christopher Berry, 32, were charged under the Official Secrets Act.

They are accused of giving “articles, notes, documents or information” to a foreign state, the Met Police in the UK said.

Mr Berry, from Witney in Oxfordshire, and Mr Cash, of Whitechapel, London, were arrested last March in connection with the investigation.

It was previously reported that one of the men - Mr Cash - was a parliamentary researcher involved with the China Research Group, and who is understood to have had access to several Conservative MPs.