"It's not just a US problem. The UK has a huge dog in this fight," he said. "They (GCHQ) are worse than the US."
The information is the latest leak from Mr Snowden, who has been responsible for a string of disclosures about US intelligence operations.
More top news
The UK's biggest ambulance service is to become the first in the country to be placed in special measures.
Footage of an armed burglar crawling on the floor of a couple's bedroom while they slept just feet away has been released by police.
Two police officers escaped unhurt after up to eight shots were fired at their vehicle in Northern Ireland.