GCHQ, the UK intelligence agency, aims to expand its remit to defend privately owned networks from hackers.
Under the plan, security teams at GCHQ would be allowed access to private networks of national significance, and search for signs of attack and take defensive action if necessary.
According to a report in the Telegraph, the prime minister recently met with firms including British Airways, BT and National Grid to discuss the plan.
Security minister Baroness Pauline Neville-Jones stated that the remit of the national cyber security hub at GCHQ will be broadened to allow it to analyse data from major communications, power and transport providers for evidence of hacking.
This is a step up from the situation today, where the Cyber Security Operations Centre provides limited intelligence on cyber threats to national security.
The report added that this proposed link with private critical infrastructure firms would swallow up the majority of the £650m funding announced last year by the government to combat the cyber threat.
It is thought that the plan has been at least partly prompted by fears of a large-scale Stuxnet-style attack on the UK's infrastructure. The Stuxnet worm was used to attack Iran's nuclear programme last year.