Threat of anthrax attack on MPs

MI5 alerted the Commons to a specific terrorist threat aimed at MPs in the House, it emerged today.

Commons Leader Peter Hain disclosed that a glass security screen was fitted across the public gallery in the Easter break after " clear intelligence" pointed to an attack.

He said the screen had been fitted on the "unequivocal recommendation " of Eliza Manningham-Buller, directorgeneralof MI5. He told MPs: "If an al Qaeda group managed to throw a phial of anthrax or ricin into the chamber - or maybe, even worse, a suicide agent released it without anyone noticing, which we have been advised is quite feasible - the particles would immediately begin spreading through the chamber. Because of the way the air flows work, within minutes total contamination could occur. Everyone, not just MPs, would be locked in, undressed and decontaminated before being allowed to leave."

MPs were voting today on whether to scrap the £600,000 temporary screen or replace it with a £1.3million permanent shield. A protester was removed from the gallery after trying to disrupt the debate. The screen made it impossible to hear what the demonstrator was shouting.

The public gallery, tiered seating looking down into the Commons chamber, is open to all visitors of any nationality. Tony Blair and most of his Cabinet could be vulnerable to an attack launched from the gallery.

All visitors to Parliament are searched for weapons and metal objects but officials fear the checks would not detect chemical or biological agents.