Russian hackers have targeted the UK energy network, telecoms and the media in the past year, a British security chief has claimed.

Moscow is "seeking to undermine the international system" and its activities are a "cause for concern", Ciaran Martin - the head of the National Cyber Security Centre (NCSC) - will tell tech chiefs.

The warning comes after Theresa May accused Vladimir Putin's state of "meddling" in elections and spreading fake news in an attempt to "sow discord in the West".

Speaking at the Times Tech Summit in London, Mr Martin will say: "I can't get into precise details of intelligence matter, but I can confirm that Russian interference, seen by the National Cyber Security Centre over the past year, has included attacks on the UK media, telecommunications and energy sectors."