A one minute's silence is to be observed at 9.33am today following yesterday's terror attack in London.
MPs, peers and staff working in Parliament and Whitehall will observe a minute's silence at 9.33am to pay respects to the victims of the attack.
The silence will follow prayers in the House of Commons at 9.30am.
A large area around the Palace of Westminster, including Parliament Square and Westminster Bridge, remains cordoned off on Thursday morning but staff were able to access the building and return to work.
Prime Minister Theresa May will lead a show of defiance in the wake of the attack, which left four people dead, including the terrorist, by giving a statement to MPs in the Commons at
Defence Secretary Sir Michael Fallon said Westminster was a sombre place in the wake of yesterday's attack, in which a police officer - PC Keith Palmer - was stabbed to death.
"The mood in Parliament will be pretty sombre," Sir Michael said.
"We've lost one of our own parliamentary police officers, who we talk to every morning going in and out of Parliament, and who gave his life to protect Parliament.
"It will be sombre, but I think you will also find determination.
"This was an attack on Parliament for a reason.
"We come together in Parliament to discuss very sharp differences, but we do so respectfully and we do so together.
"That's not what terrorists believe in, that's not what they want.
"It's no accident that this was an attack on Parliament, and I think you will find a very real determination and solidarity that we reinforce the values that keep us together."