British Prime Minister David Cameron arrives at the EU council headquarters for the second day of a European Union leaders summit addressing the talks about the so-called Brexit and the migrants crisis in Brussels, Belgium REUTERS/Yves Herman

Britain floated revised legislation on Tuesday that would grant authorities wide-ranging surveillance powers including the right to see which websites people visit, saying the modified bill addressed concerns about threats to privacy.

Last November, Prime Minister David Cameron's government unveiled a draft of the law that would give police and spies snooping tools they say are vital to protecting the public from criminals, pedophiles and terrorism.

But the measures met scepticism from lawmakers, global technology firms and privacy groups, reflecting a debate raging in the West over how state authorities can operate effectively in the digital age without overly intruding into people's lives or risking the security of data.

On Tuesday, the Conservative government put forward a tweaked version that it said was clearer and provided stronger privacy safeguards.

"The bill ensures that the security and intelligence agencies and law enforcement continue to have the powers they need to keep us safe - and no more," Home Secretary (interior minister) Theresa May said in a foreword.

Earlier this month a committee of lawmakers set up to scrutinize the draft bill said the government needed to make significant changes, describing parts as flawed, while the Intelligence and Security Committee (ISC) said it was rushed and did not do enough to protect privacy.

Last year's draft bill was itself a watered-down version of plans dubbed a "snoopers' charter" by critics who prevented it reaching parliament.

The revised proposal seeks to spell out existing powers, update outdated legislation and grant additional capabilities.

Its measures include forcing tech firms to store details of every website people visit for a year, and outlines the ability of spies to collect bulk data and for the authorities to hack into individuals' computers and smartphones.

The British bill needs to be passed into law before the end of the year when existing surveillance legislation expires.

Critics remained unimpressed.

"The bill published today continues to adhere to the structure and the underlying rationale that underpinned the draft ... bill, despite the criticism and lengthy list of recommendations from three parliamentary committees," said Gus Hosein, Executive Director of Privacy International.

One of the most contentious issues has revolved around whether tech firms would have to hand over data they held even if was encrypted. May said companies would only be asked to produce data protected by encryption where it was "practicable".

That might address the concerns of global tech giants such as Apple, which is engaged with a showdown the FBI over its refusal to unlock an iPhone belonging to Syed Rizwan Farook, who along with his wife went on a shooting rampage in December that killed 14 people in San Bernardino, California.

Apple says unlocking the phone would weaken the security of hundreds of millions of Apple devices.

Reuters