The Defence Select Committee said new Type 45 destroyers being developed for the navy may not come into service until 2007 - eight years after the first of the ships they are designed to replace goes out of service.

The MP's said the delay meant there may be a "looming gap in our anti-air warship capability".

The new destroyers will replace the Type 42 ships currently deployed, which are being decommissioned at six-monthly intervals begining in late 2006.

Eight-year gap

However, one ship, HMS Birmingham, will leave service later this year.

The MP's expressed concern that the overlap between HMS Birmingham and the first of the remaining Type 42s being decommissioned and the arrival of the new ships will leave the navy understrength.

The committee said: "With the Type 45s to be built in batches - as is usually the case - they are unlikely to be commissioned at the same rate as the Type 42s depart.

"While it is sensible not to run old ships with expensive running costs and increasingly obsolescent systmes, it makes less sense to decommission them before their capability is replicated."

The MPs added: "HMS Birmingham will leave service later this year, so for the next eight years the Royal Navy will have to make do with one less anti-air platform".

The committee recommended that the Ministry of Defence re-examined the Type 42 decommissioning schedule to avoid a drop in numbers in UK anti-aircraft ships.