An urgent review is under way into the security breach at Westminster that saw two protesters scale Big Ben, Commons Speaker Michael Martin confirmed yesterday.

Mr Martin said he took the incident extremely seriously and had personally inspected the area where Greenpeace demonstrators Harry Westaway, 28, and brother Simon, 23, from Lewes, broke in at the weekend to protest at the Iraq war.

He told the Commons: "I have received a full report from the head of security and have inspected the area where the breach took place.

"An urgent review is being undertaken - both of the security precautions in that particular area and of the security arrangements as a whole."

Mr Martin added: "I informed the senior officers of the house responsible for security to get to a meeting this morning and I informed those officers not to meet in my study but to get their overcoats on because they were going outside to see exactly where this breach took place."

The Greenpeace protesters, whose demonstration lasted seven hours, later described overcoming Parliament's defences as easy.

They were bailed by police after being arrested on suspicion of causing criminal damage.

They were ordered to return to a central London police station next month.