Anti-war protesters bombarding MPs with images of dead babies and severed heads have prompted Commons calls for a review of politicians' security.
Shadow Commons leader Chris Bryant highlighted abuse targeted at MPs planning to support bombing of Islamic State in Syria.
Several MPs saw protests outside their constituency office and Labour's MP for Walthamstow Stella Creasy reportedly had protesters outside her home ahead of the crunch Commons vote.
Commons leader Chris Grayling said security was a "continuing priority" adding MPs must be allowed to express views in a "free and unfettered" way.
He told the House, while MPs should expect scrutiny, they should never be subject to illegal acts.
Speaking at the weekly business statement, Mr Bryant said: "Many people have over the last few days hurled a great deal of abuse at members for their views on whether or not the House should extend air strikes to Syria.
"Some have been called murderers, peaceniks, terrorist sympathisers, whatever. I hope you would agree that whilst all MPs expect a certain degree of hurly burly in political life, it is a fundamental principle all MPs are sent not as delegates but as representatives with the full power to exercise their judgment and their conscience and to speak and vote without fear or favour.
"No MP should ever be intimidated. Sadly, some of the abuse, I think we would all agree, has been beyond the pail. Several MPs have had their offices barricaded, one MP had her house surrounded. Many had photos of dead babies pushed through their front door at home.
"I gather today some MPs have received photos of severed heads. MPs have broad shoulders, of course we do, but can I ask you to review arrangements regarding security of MPs homes and offices. It's not just about MPs, it's also about their families and their staff.
"In particular can you look at whether the responsibility for funding these matters should now be taken away from Ipsa (Independent Parliamentary Standards Authority) and restored to the House authorities?"
Responding, Mr Grayling praised the "brave" decision Mr Bryant took in backing the Government on military action.
He told MPs: "I mentioned a couple of weeks ago the security of MPs and the need to protect them against criminal activity.
"We are all subject to legitimate public scrutiny but it will never be acceptable for MPs' personal safety to be in jeopardy, it will never be acceptable for MPs to be the victim of activities a court would judge illegal.
"We would never in this House discuss security arrangements for members but suffice to say it is and will be continuing as a priority for the (House of Commons) Commission, a priority for the House authorities.
"We need to do everything we possibly can to protect the rights of members to express their views in a free and unfettered way and protect them when they do so."
In other answers, Mr Grayling confirmed MPs would be given updates on the military strikes in Syria before the Commons breaks up for the Christmas recess on December 17.
He said: "Following yesterday's debate, when MPs on both sides said they would expect regular updates on the situation in Syria, can I inform the House the Government intends to provide a proper update statement before the Christmas recess?
"I'm sure the whole House will want to join me in sending good wishes to the British air crew involved in action overnight."