A total of 139 knives were seized from visitors to the House of Commons last year, new figures show.
Police also took 63 sprays, most of them believed to be self-defence canisters, and nine other weapons at the entrance to the Palace of Westminster.
The majority of items are thought to have been seized from tourists from countries whose laws on carrying were less strict than in the UK.
The previous year, 150 knives and 54 sprays were confiscated.
The new figures were collected by think tank Parliament Street under Freedom of Information rules.
Its director Clare George-Hilley said: “These figures demonstrate the very real threats facing Parliament and underline the need for rigorous and robust checkpoint security measures to ensure the safety of the House of Commons.”
In previous years police have seized imitation firearms, coshes, knuckle dusters, meat cleavers and even a sling shot.
In 2009 officers confiscated 132 knives and 40 sprays; in 2010 they seized 126 knives and 42 sprays; and in 2011 they took 148 knives and 42 sprays.
Security at Westminster was tightened after a series of security breaches. In 2004 Tony Blair was struck by a condom filled with purple powder during Prime Minister’s Questions. Five protesters opposed to the proposed ban on fox-hunting disrupted proceedings by running into the chamber.
Now police check visitors by using airport-style X-ray machines and searches. A Metropolitan police spokeswoman said: “Almost 400,000 visitors attend the Palace of Westminster each year and these figures reflect the fact that we operate a successful search regime.
“We take security issues very seriously. Where an item is identified as potentially an offensive weapon, these are retained by the police. An officer may use their discretion on any further action to be taken.
“There is always a balance to be struck between providing appropriate security and allowing the public and other visitors legitimate access to buildings and other locations.
“In the vast majority of cases, these items are carried by visitors to the UK who may not be familiar with UK law, and where there is no suggestion of criminal intent.”
