Part of the Mall in London, which leads to Buckingham Palace, was closed as officers dealt with the item.

The devices follow a coded threat issued to Scotland Yard by republican dissidents yesterday - but Irish police have vowed it will not alter their security plans.

The telephone threat contained a recognised code word, but did not specify a time or place.

Superintendent John Gilligan said: "Our plan has been in place for a number of weeks.

"Officers from the UK are also part of the plan which is large enough to allow the visit to be conducted in the proper fashion."

On Sunday the Met Police

A massive security operation has been launched in Dublin ahead of the Queen's arrival today.

Police are patrolling the streets, parking is prohibited in many areas and large swathes of the city are being closed off.

More to follow...