Rishi Sunak has challenged the Chinese premier, Li Qiang, over Chinese interference in the UK parliament, after two men were arrested amid allegations that a parliamentary researcher had spied for Beijing. The prime minister met Li on the sidelines of the G20 summit in Delhi in an unplanned meeting hours after the Sunday Times revealed the researcher, who is understood to have had links to senior Conservative MPs, had been arrested along with another man. After the meeting, Sunak said: “I obviously can’t comment on the specifics of an ongoing investigation but with regard to my meeting with Premier Li what I said very specifically is that I raised a range of different concerns that we have in areas of disagreement, and in particular, my very strong concerns about any interference in our parliamentary democracy, which is obviously unacceptable. “We discussed a range of things and I raised areas where there are disagreements. And this is just part of our strategy to protect ourselves, protect our values and our interests, to align our approach to China with that of our allies like America, Australia, Canada, Japan and others, but also to engage where it makes sense.” According to Chinese media, Li told Sunak the two countries “should properly handle disagreements, respect each other’s core interests and major concerns”. The meeting had not been scheduled, but was confirmed on Sunday morning after news of the arrests broke. The issue was the first thing Sunak raised during their 20-minute encounter, to which Li responded that the two countries had “differences in opinion”. The pair also spoke about trade, Ukraine and artificial intelligence. They did not talk in detail about the AI summit in the UK later this year, however, despite reports that Britain had issued an invitation to China to attend. Last month, James Cleverly became the first foreign secretary in five years to visit China and said during the visit that it would not be “credible” to disengage with Beijing. Sunak, meanwhile, has angered China hawks in his own party by refusing to say the country is a threat to Britain. He said earlier this year: “I don’t think it’s kind of smart or sophisticated foreign policy to reduce our relationship with China – which after all is a country with one and a half billion people, the second biggest economy, and member of the UN security council.” The prime minister has also refused to rule out inviting China to his summit on artificial intelligence later this year. The latest row over Chinese espionage at the heart of British democracy risks damaging any detente between the two countries, however. The Sunday Times said the researcher, who is in his 20s, and another man in his 30s had been arrested in March. The man, who is a UK citizen, reportedly had links to Alicia Kearns, the Conservative chair of the foreign affairs select committee, and Tom Tugendhat, the security minister. Officers from the Metropolitan police’s counter terrorism command, which oversees espionage-related offences, are investigating. The man in his 30s was arrested in Oxfordshire on 13 March , while the man in his 20s was arrested in Edinburgh, Scotland Yard said. Both were held on suspicion of offences under section one of the Official Secrets Act 1911, which punishes offences that are said to be “prejudicial to the safety or interests of the state”. “Searches were also carried out at both the residential properties, as well as at a third address in east London,” a statement from the force said. Both men were held at a south London police station until being bailed until early October. Tugendhat is said not to have had any contact with the researcher since before he became security minister in September last year. Kearns declined to comment, adding: “While I recognise the public interest, we all have a duty to ensure any work of the authorities is not jeopardised.” Both Kearns and Tugendhat have angered Beijing in recent years. Kearns has made a number of remarks about the threat China poses to British security and sovereignty. Meanwhile, Tugendhat infuriated the Chinese government earlier this year when he met the Taiwanese digital minister in the UK. China considers Taiwan part of its own territory. A Whitehall source told the Sunday Times: “This is a major escalation by China. We have never seen anything like this before.” The arrests follow several high-profile warnings about Chinese spying in the UK. In July, the Commons intelligence and security committee warned China was targeting Britain “prolifically and aggressively”. MPs on the committee also warned the government did not have the “resources, expertise or knowledge” to tackle the threat.