Foreign Secretary William Hague issued a warning on Wednesday to countries which sponsor cyber attacks, at the close of a global cyberspace conference in London.
He would not name and shame those responsible, saying the two-day talks were intended to be "constructive", but government advisor Pauline Neville-Jones said on Monday that Russia and China were "certainly some of them".
"State-sponsored attacks are not in the interests of any country long term, and those governments that perpetrate them need to bring them under control," Hague told delegates in his closing statement.
He told reporters later: "We have and we will have... in the future vigorous private discussions about this, particularly if our ability to detect cyber attacks and the source of them improves."
The conference, involving over 700 officials, security experts, technology firms and NGOs from more than 60 countries including Russia and China, failed to reach any formal agreement on the broad range of issues discussed.
But Hague said the talks made "important progress" towards setting out a global agenda, which will be followed up in conferences in Hungary in 2012 and South Korea in 2013.
Both Hague and US Vice President Joe Biden, who addressed the meeting via videolink on Tuesday, had pressed the need for Internet freedom, and despite acknowledging a difference of opinion, Hague said most delegates agreed.
"There is a difference between British, American, European societies on the one hand and China, a different political system (with) different attitudes to freedom of expression offline as well as online," he told reporters.
But in his final statement he insisted: "There was overwhelming support for the principle that cyberspace must remain open to innovation and the free flow of ideas, information and expression."
Hague said there was "no appetite" to develop new legally-binding treaties on the Internet, and said speakers had tended to back "a transparent and stable framework of self-regulation" rather than any government intervention.
However, most agreed that better global cooperation and collaboration was needed "to avoid misunderstandings", Hague said.