The Met paid £2m to informants

Scotland Yard paid £2,131,786 in rewards for information about criminals operating in London and elsewhere during the last financial year.

The figures, contained in documents obtained by the Press Association, shine a rare light on one of the most secretive areas of modern policing.

The Met, like others forces in England and Wales, consistently refuses to disclose its spending on informants, even after Freedom of Information requests.

The spending emerged as the senior officer responsible for covert operations said the force is on an informant recruitment spree. Assistant Commissioner Bob Quick said informants, known in police-speak as "covert human intelligence sources", are an essential weapon against crime.

Mr Quick, who is responsible for counter terrorism, diplomatic and Royal protection at the Met, said they are "extraordinarily cost effective".

But he admitted using informants was a "moral maze" which police officers alone should not be left to navigate.

He said: "Safeguards are used on a daily basis to make sure we are on moral terra firma and make sure we act as professionals in dealing with high risk individuals and high risk intelligence.

"The British Security Service will share the Metropolitan Police view that this is the future. It is an area we are attempting to develop because of its cost effectiveness and its ability to protect the public, so there is a lot of work to be done there."

Critics fear informant handling procedures could be abused by officers because large amounts of cash changes hands under a cloak of secrecy. Members of the Metropolitan Police Authority, the force's board of governors, plan to meet behind closed doors in the near future to discuss the matter.