AT least 22 unexploded Second World War bombs are buried on the Tendring coast, according to new research.

An estimated 226 devices were dropped in the Frinton and Walton area, which covers from Harwich to St Osyth, during the conflict.

It is thought at least 10 per cent did not detonate.

Site investigation firm Zetica, based in Oxfordshire, has produced bomb risk maps for the entire UK.

Researchers used archives from the Ministry of Defence and local authorities to plot where bombs were dropped.

The Harwich area is considered high risk which means 50-plus bombs per 1,000 acres were recorded.

The stretch from Walton to St Osyth is considered moderate risk, a density of 11 to 50 bombs per 1,000 acres.

Closer to London, where there were a greater number of military, utility and industry targets, the number of unexploded devices are much higher.

The Burnham-on-Crouch area saw an estimated 376 bombs dropped, the Southend area 427 and Thurrock 1,799.

Mike Sainsbury, managing director of Zetica, said: “We had expected to find a high amount of bombs in the East Anglian coast because it contained some important targets and was an easy area for the Germans to get to.

“I believe it was Hitler's own personal goal to strangle London by targeting docks.”

Bombs often entered the ground unnoticed at high speed and penetrated several metres.

They can still pose a threat to activities such as piling, drilling, tunnelling and excavations in high risk areas.

An unexploded shell was found in a ditch near Two Village Primary School in Ramsey in January 2006 and a resident dug up an incendiary device in his the garden in Main Road, Dovercourt, in August 2006.

More recently a 1,000lb shell – one of the largest ever to be found on Britain's coastline - was washed up on Felixstowe beach in April.