GCHQ, the government's electronic eavesdropping and security agency, is to warn the chief executives of Britain's biggest companies about an unprecedented threat from cyber-attacks.

Ministers and the intelligence agencies are for the first time confronting senior private sector company figures over their failure to protect their businesses from cyberthreats to their personal data, online services and intellectual property.

"GCHQ now sees real and credible threats to cybersecurity of an unprecedented scale, diversity, and complexity", said Ian Lobban, the agency's director.

There have been determined and successful efforts to steal intellectual property, access defence information and disrupt government, he says in a foreword to a GCHQ publication, an "Executive Companion - 10 Steps to Cyber-Security".

Thousands of IT systems are compromised every day, he says, some for political motives, but most commonly to steal money or commercial secrets.

The magnitude and tempo of the attacks pose a real threat to Britain's economic security', Lobban adds. About 80% of known attacks would be defeated by embedding basic information security practices.

The business secretary, Vince Cable, said: "Cybersecurity threats pose a real and significant risk to UK business by targeting valuable assets such as data and intellectual property. By properly protecting themselves against attacks companies are protecting their bottom line."

The foreign secretary, William Hague, the minister responsible for GCHQ, said: "The UK is committed to building a secure, resilient, open and trusted internet … But cyberspace – and cybercrime – knows no borders. Businesses must be alert to the dangers."