Britain's Prime Minister Theresa May visits a joinery factory in London, Britain August 3, 2016. REUTERS/Neil Hall - RTSKW9G

LONDON (Reuters) - An independent review of draft British security legislation said bulk interception and collection of citizens’ personal data was vital for the intelligence agencies to prevent attacks, a position welcomed by Prime Minister Theresa May.

Last November, Britain unveiled a draft of the law that would give police and spies broad snooping powers they say are vital to protecting the public from criminals, paedophiles and terrorism.

David Anderson, the Independent Reviewer of Terrorism Legislation, said in a report that bulk interception was of “vital utility” to the security services while there was no alternative to collecting large amounts of data on people unlikely to be under suspicion, known as bulk personal datasets.

“Anderson’s report demonstrates how the bulk powers contained in the Investigatory Powers Bill are of crucial importance to our security and intelligence agencies,” May said in a statement.

“These powers often provide the only means by which our Agencies are able to protect the British public from the most serious threats that we face,” May said.