Google has expressed shock following a report that the US National Security Agency (NSA) has hacked its data links.

An executive at Google said it was not aware of the alleged activity, adding there was an "urgent need for reform".

According to source, the comments follow a Washington post report, based on leaks from Edward Snowden claiming that the NSA hacked links connecting data centers operated by Google and Yahoo.

The revelations stem from documents leaked by ex-US intelligence contractor Edward Snowden, who has been granted temporary asylum in Russia and is wanted in the US in connection with the unauthorized disclosures.

The documents say millions of records were gleaned daily from the internet giants' internal networks.

It suggested that the NSA intercepted the data at some point as it flowed through fibre-optic cables and other network equipment connecting the companies' data centers, rather than targeting the servers themselves.

While commenting on this, the NSA director Gen Keith Alexander however had claimed it had not had access to the companies' computers.

"We are not authorized to go into a US Company’s servers and take data." he said