Obama holds cybersecurity summit [668]

The meeting at Stanford University in California will bring together industry and law enforcement.

It follows Obama's launch of an intelligence unit to co-ordinate analysis of cyber-threats.

A senior member of Britain's National Crime Agency is also due to appear, along with executives from Microsoft, Facebook and Google.

Mr Obama "wants to build support for efforts to better protect against cyber-threats and share more information about cyber-attacks", the White House said.

The figures are appearing at a White House summit, but one that the president has chosen to hold in Silicon Valley, rather than in Washington DC.

According to reports, Mr Obama, who will be joined at the summit by top US security officials, is planning to call on private tech firms to share more information with law enforcement, potentially placing him at odds with the companies.

If he does so, he will be following in the footsteps of the British prime minister, who said in January that forms of communication that are resistant to surveillance measures should not be allowed.

His comments were interpreted as a direct attack on encrypted communications, such as Apple's FaceTime and Microsoft's Skype, among others.

The conference, which will also focus on how to protect consumers online, is taking place in the aftermath of the hacking scandal that hit Sony Pictures and which the US authorities blamed on North Korea.

America and China have also taken more aggressive stances towards each other over cybersecurity recently, with the USA charging a series of Chinese people with hacking last year.

The French authorities beefed up their security efforts after claiming to have detected attempts to launch cyber-attacks in the aftermath of the Paris terror attacks. And just this week the Dutch government fell victim to a distributed denial of service attack, which took many of its websitessites down by flooding them with traffic.

Announcing the summit last month, Mr Obama said cybersecurity was a "challenge that we can only meet together".

"It's going to bring everybody together - industry, tech companies, law enforcement, consumer and privacy advocates, law professors who are specialists in the field, as well as students - to make sure that we work through these issues in a public, transparent fashion," he said.

He is due to address the conference at 19:15 GMT. Besides Mr Cook, other speakers include Google vice-president Eric Grosse, Facebook chief information security officer Joe Sullivan and his Yahoo counterpart Alex Stamos.

Microsoft vice-president Scott Charney and chief executives from Visa, MasterCard and American Express will also appear.