The parliamentary authorities have agreed to appoint a new security coordinator.

The move announced in a written answer on Tuesday follows a review of parliament's internal policing procedures prompted by a series of recent breaches.

The new security chief with oversee both the Commons and Lords - providing peers vote for the combined appointment.

Leader of the House Peter Hain quickly called for a new post of security chief to be created in the wake of the invasion of the Commons by pro-hunt campaigners last month.

The Fathers4Justice purple powder attack on Tony Blair during a session of prime minister's questions in May - and a Greenpeace protest on Big Ben in March - also sparked fresh fears over the Palace of Westminster's defences against a potential terrorist attack.

The new coordinator is set to take power away from the "men in tights" - the former Army officers who have traditionally been in charge of the parliamentary premises and accountable only to MPs and peers.

The Metropolitan Police and the security services are expected to play a much more significant role in protecting the building if both houses support the proposals from the Commons commission.