The House of Lords will investigate how three protesters were able to get around parliamentary security to protest during the visit of Canadian Prime Minister Stephen Harper, a spokesman said.
Activists demonstrating during Canadian prime minister Stephen Harper's visit to Parliament have been arrested.
Scotland Yard said three people were arrested after a protest at the Sovereign's Entrance.
Environmental campaigners against "tar sands", a form of fuel which produces more emissions than conventional oil, have posted a video showing them on the roof of Parliament, with a statement saying they wanted to disrupt the premier's address to MPs and peers.
Shortly before Mr Harper's speech the doors slammed shut on the robing room, where the Queen puts on the Imperial State Crown and her ceremonial robes for the state opening of Parliament, and shouting was heard.
Baroness Thatcher's coffin lies in a chapel in Parliament, draped in the Union flag with a message saying 'Beloved Mother - Always in our Heart'.
Commons speaker John Bercow has announced that the bells of Big Ben and the Great Clock at Westminster are to be silenced during the funeral of Baroness Thatcher on Wednesday.
The House of Commons authorities has said the last time the bells were silenced were for Winston Churchill's funeral in 1965, except in the 1970s when they broke down.
The bells of Big Ben and the Great Clock at Westminster are to be silenced during the funeral of Baroness Thatcher on Wednesday, Speaker John Bercow has told the House of Commons:
The Crown Prosecution Service has said there was "insufficient evidence" that Eric Joyce MP had committed an offence after he was arrested on suspicion of assault and ABH following an incident outside a bar in the House of Commons.
Police are not going to take any further action over the MP Eric Joyce after he was arrested on suspicion of assault and ABH following an incident outside a bar in the House of Commons.
The MP arrested after an alleged brawl in a parliamentary bar denied he was drunk at the time and hit out at claims he was an alcoholic.
In a posting on his website, Eric Joyce insisted he had consumed "by any standards a very modest amount" and criticised a decision by officials to bar him from drinking at Parliament.
And, amid calls for him to quit after the second such incident in recent years, he defended his "diligence" as the independent constituency MP for Falkirk.
Mr Joyce resigned from the Labour Party last year after being fined and handed a three-month pub and bar ban for punching and head-butting fellow MPs.
He was arrested on suspicion of assault on Thursday after an altercation at the Sports and Social Club apparently over taking a glass out to a smoking area.
The former soldier was released on bail yesterday.
The MP said he was limited in his responses to reports about him as he wanted to "respect the police inquiry".
But in a series of points he sought to correct what he said were false reports about his health and general behaviour.