Britain and the United States will increase cooperation on cyber security, setting up "cyber cells" to share intelligence and conduct simulated attacks to test the defences of organisations such as banks.

British Prime Minister David Cameron is on a two-day visit to Washington focused on the economy and security and is due to have a second meeting with President Barack Obama later on Friday (January 16).

In an interview broadcast on Friday, Cameron told the BBC that the two countries' "hugely capable" cyber defences and expertise would be combined to set up cyber cells on both sides of the Atlantic in order to share information.

The cooperation between Britain's GCHQ eavesdropping agency and the US National Security Agency will include joint war games, with the first exercise later this year to involve the Bank of England and commercial banks in both the City of London and Wall Street, the BBC reported.

The British leader said he also planned to discuss with Obama how the two countries could work more closely with big Internet companies such as Facebook and Google to monitor communications between terror suspects.

The head of Britain's MI5 Security Service has echoed that concern over lack of access to communications, warning last week that Al Qaeda militants in Syria were plotting attacks to inflict mass casualties in the West.

Cameron has said if he is re-elected in a national vote in four months time, he will bring in new laws to give security and intelligence services greater powers to monitor Internet communications.