Timebomb ready to blow

For 60 years the rotting masts of the SS Richard Montgomery have poked eerily from the sea at low tide, surrounded by buoys.

Small signs attached to the masts inform those who sail by on the Thames estuary: "Danger: unexploded ammunition." There are 3,172 tonnes of high explosive in the forward holds.

The ship foundered 60 years ago tomorrow in the mudbanks of the Medway, a mile from the Kent port of Sheerness. Today it is claimed the cargo of 13,700 bombs is a disaster waiting to happen.

If the Second World War American cargo ship was to blow up, a report warns, it would be one of the biggest non-nuclear explosions ever and could devastate Sheerness (population 11,000). Experts estimate the force of the blast would be 700 times that of the 1995 Oklahoma City bomb in the US. The Montgomery put in to the estuary in 1944 on its way to Cherbourg with bombs for the US air force. After she ran aground and started to break up, the Admiralty ruled salvage too costly.

Now, a report in New Scientist magazine says the munitions have unprotected fuses which could turn highly unstable if exposed to water vapour, and there could be a spontaneous explosion should water penetrate the bombs.

In 1999 a risk assessment was commissioned by the Government, but the report has not been published. In 2001 the Maritime and Coastguard Agency felt it was time to act, said New Scientist. "A terrorista collision with another vessel-or even the small shock of a bomb moving in the tide could set off the explosives," the magazine claimed.

Tests in 1970 showed that a blast at low tide, when the wreck is covered by only 36ft of water, would hurl a 1,000ft-wide column of mud, metal and munitions almost 10,000ft into the air, shattering every window in Sheerness and causing widespread damage to buildings. No assessment was made of likely injuries or loss of life. The 1999 report outlined five options for dealing with the wreck, said New Scientist, including burying the ship in concrete, or building a sandbank and ditch around her before removing the cargo - which would require the evacuation of Sheerness.

A Department of Transport spokesman said the risk assessment is unfinished and not yet ready for publication. "It needs more work to accurately predict the likely risks of an explosion."