A 23-year-old man has been arrested on suspicion of rape after an alleged attack in the Houses of Parliament.
The attack is alleged to have happened in the early hours of Friday (14 October), and the man was arrested that day, said the Met Police in a statement.
Officers were called to Westminster after the victim raised the alarm.
The suspect has not been named, but police stressed that he was not an MP. He has been bailed "pending further inquiries", said police.
According to reports he works for a Conservative MP, whose office has also been searched.
Parliament is "working closely" with police, the House of Commons said.
"We are aware of an incident on the parliamentary estate which is being investigated by the Metropolitan Police Service," a spokesman said.
"Parliament is working closely with the police on their investigation and we cannot comment further while this is ongoing."