The speaker of Britain's Parliament says security is being strengthened after a trespasser spent more than eight hours on the roof of the House of Commons.

John Bercow said Monday that "immediate remedial actions" have been taken to address security failings. He says security officials will publish a report Tuesday into the incident.

Police were called Saturday evening after a man was spotted among the elaborate cornices atop the 19th century neo-Gothic building. He was arrested just before dawn on Sunday.

Braydon Liam Anderson, who is 23, was charged with criminal damage and trespassing on a protected site.

The Parliament building has tight security and is guarded by armed police. But campaigners have previously scaled it to oppose the construction of another runway at Heathrow and protest climate change.