Security arrangements at the UK Parliament are to be reviewed following Wednesday’s attack in London.
Some of the entrances to the Palace of Westminster are already guarded by heavily-armed officers.
But the terrorist who breached the site’s perimeter managed to rush through the carriage gates used by ministers and MPs.
Constable Keith Palmer, who was fatally stabbed, was not armed.
Defence Secretary Sir Michael Fallon said yesterday the review would examine whether current security arrangements were “adequate” and whether police at the front gates should be armed.
But he argued it was neither possible nor desirable to seal parliament off from the public.
In the Commons yesterday, former Northern Ireland Secretary Theresa Villiers said police should consider arming all officers protecting “sensitive sites”.
The Tory MP asked: “As we reflect on what happened, is it time to consider whether the police, who guard sensitive sites known to be of interest to terrorists like parliament or airports, should routinely carry personal protection weapons, even when those officers are not part of the units formally tasked with armed response?”
Theresa May, who was in the chamber to update MPs on the attack, responded the level of security had “been enhanced significantly” during her 20 years in parliament.
The prime minister added: “As to whether individual officers undertaking particular duties are routinely armed, that is an operational matter for the police themselves.
“They are the best able to judge the circumstances in which it is best for individuals to have such arms.
“Of course, we have seen a significant increase in the number of armed response vehicles and the number of counter-terrorism specialist firearms officers.
“It is a sad reflection of the threat that we face that it has been necessary to do that.”