The Scotland Yard, Britain's premier police force, has been accused of being opaque and trying to withhold information from public about crimes by adopting an 'if asked' policy.
Under the policy, information about cases were only to be disclosed if a reporter has heard about them elsewhere and asked for confirmation.
A Freedom of Information request by The Times newspaper found that almost 50 per cent i.e. 4,877 of 9,906 crimes recorded with the Metropolitan Police press office in the five months until February were logged 'if asked'.
The policy has raised concerns about transparency about the police force already reeling under a series of scandals.
Keith Vaz, Britain's senior-most Indian-origin MP and chairman of the House of Commons' Home Affairs Select Committee, warned that the system could be used to hide information that might be embarrassing to Scotland Yard, or were in public interest.
"It worries me that issues are being kept waiting for someone with the time and inclination to ask questions, rather than to be in a position to be open and transparent" he said.
A spokesperson for the force, however, said that many of the incidents were only initially labelled 'if asked' and then given to journalists once their true nature were established.
Human rights activists feel the high number of logs raises concerns about transparency.
"The Met and the police more generally need to re-establish trust with the public. This seems to be pointing in the opposite direction," said Robert Barrington, executive director at Transparency International.
The Metropolitan Police has already been struggling to contain a row over covering up "institutionalised sexism" within the force.
It is also battling allegations of corruption after the UK government published a report last week, saying that police officers investigating the murder of a black teenager, Stephen Lawrence, tried to smear people close to the teenager.
It led to Britain's most senior counter-terrorism officer, Commander Richard Walton, being removed from his post.