The female police officer who was arrested over alleged media leaks about the "plebgate" affair was present at Downing Street during the time of the incident in September, the Metropolitan Police said.
A 46-year-old female police officer from Scotland Yard's Diplomatic Protection Group was arrested over alleged leaks to the media linked to the Andrew Mitchell "plebgate" affair, the Metropolitan Police said.
A 46-year-old male officer arrested yesterday has been bailed to return on a date in March.
David Cameron said it was "very important" the investigation into the 'plebgate' affair was "thoroughly carried out and proper answers are delivered".
The Metropolitan Police said the allegations against the officer arrested today are "extremely serious" and the investigation continues with "urgency, determination and an open mind."
The latest information from Scotland Yard reveals there are now six officers and one civilian arrested or being investigated over the Andrew Mitchell "plebgate" incident.
The man arrested over alleged leaks to the media linked to the "plebgate" affair was not one of the officers at Downing Street during the incident in September 2012, the Metropolitan Police said in a statement.
A police officer responsible for protecting Government officials has been arrested over alleged leaks to the media about the "plebgate" incident.
The 46-year-old from the Diplomatic Protection Group was held at his work place in central London on suspicion of misconduct in public office.
Public confidence in the police force has been shaken because of a "dangerous cocktail" including the "plebgate" affair and the results of the Hillsborough Inquiry, a senior Labour backbencher has said.
Keith Vaz MP, chair of the Home Affairs Select Committee, which will start an inquiry into police accountability, integrity, internal corruption and malpractice in January, said it is a "defining moment" for the service.
He called on Prime Minister David Cameron to host annual summits with senior officers and called for "a new Magna Carta" for policing.
In the Sunday Express, Mr Vaz said recent events had dented the public's confidence in the police.
Met Commissioner breaks off Xmas holiday citing concerns about welfare of 'plebgate' officers as a paper apparently identifies one.
The Met Police (MPS) now has 30 detectives investigating Plebgate with "numerous lines of inquiry" into what happened in Downing St three months ago.
The force has revealed the scope of its inquiry: