A Hamilton construction site could have suffered explosion damage yesterday after a worker came across three live 19th Century artillery shells while digging the foundations to a new office block.

"There is a remote chance they might have gone off if they had been struck," said Police explosives expert Sgt. Stephen Cosham, who was called in to look after the 200 to 250 pound rounds before they were taken away for safe disposal.

The discovery is the second at the site in as many months.

In May two other shells were found at the East Broadway location where Renaissance Reinsurance is having a four storey office block built adjacent to its headquarters.

Construction worker Kevin Burchall, who made yesterday's find, said: "I was digging with the excavator and I just saw these points sticking at me. It's one of the dangers of this job. I'm glad they didn't go off. Finding something like this makes you a bit wary of digging."

Sgt. Cosham, who works with the Police's Explosive Ordnance Disposal Team, said: "They're live and you have to treat them with respect. We are being precautionary but there is a real chance of them exploding."

He said the Pallster shells, each of which date from between 1820 and 1870 and carry about ten pounds of gunpowder, were most likely intended for use by the Royal Navy in defending against ships.

And he explained the type of round was used in only a few places in the world including Bermuda and were the first example of rifling for cannons, meaning that they would spin when fired in order to make them more accurate.

"The weight of the shell alone would be able to do massive damage to a wooden ship."

Sgt. Cosham said, adding that there were recorded cases of people finding such objects and taking them home to see what is inside them by cutting into them.

"The explosives themselves would do some damage but the fragmentation would do enormous damage to anything within 100 metres."

He explained that the weapons would have to be taken down to the explosive bunkers at the end of Weapons Pier at Bermuda International Airport.

They will then be destroyed by a weapon called a Point Focal, which fires a small cylindrical charge right through the shell and ignites the explosives, the energy from which will then hopefully escape through the hole in the other side.

But the procedure isn't foolproof by any means: "I guess there is a 50 per cent chance of them exploding," said Sgt. Cosham. "We will of course be a long way away from the bunkers."

He added that such finds are not as rare as one might expect.

"We find them about five or six times a year. It's not uncommon, especially with the Island's Royal Naval history."

Asked how he reacted when finding the shells, site superintendent Marcelino Ferreira said: "I was just being diligent and I immediately responded by calling the Police."