The head of GCHQ has called for greater co-operation between tech firms and state surveillance agencies - particularly in agreeing stances over granting access to encrypted networks.

Speaking an event at MIT in Boston, Robert Hannigan director of the UK government's communications intelligence agency, said that the security offered by tech firms is being misused by a small number of people.

"We need a new relationship between the tech sector, academia, civil society and government agencies. We should be bridging the divide, sharing ideas and building a constructive dialogue in a less highly-charged atmosphere," he told the audience.

He spoke as the standoff continues between the FBI and Apple, the Californian firm has refused to create a programme to allow US authorities to unlock the iPhone of Syed Farook, who together with his wife Tashfeen Malik, killed 14 people in San Bernardino, California in December of last year.

Mr Hannigan said that the decision regarding what information is and is not accessible should be decided by politicians, not spies or companies.

"The solution is not, of course, that encryption should be weakened, let alone banned. But neither is it true that nothing can be done without weakening encryption," he added, during a speech which highlighted the contribution that British intelligence agencies made to the creation of modern encryption.

The British government intends to introduce a new investigatory powers bill which will ban end-to-end encryption, such as that used on Apple's phones.

He asked companies to cooperate with the State, saying, "Within the parameters set by legislation, it should be possible for technical experts to sit down together and work out solutions to particular manifestations of the abuse of encryption."

Apple has argued that creating backdoors in encrypted networks creates a backdoor for "everyone." CEO Tim Cook said last month that accessing user information would "undermine the very freedoms and liberty the government is meant to protect."