Eight of the world’s leading technology firms including Google, Apple and Twitter have formed an alliance calling for changes to US government surveillance.

In a letter to Washington the companies argue that current surveillance practice undermines the freedom of the people.

It follows recent leaks about the extent of government “snooping” which have revealed that the collection of phone records, the tapping fibre-optic cables that carry global communications and the hacking of networks have been accepted practice.

The firms think that surveillance should be controlled.