By Penny Spiller
BBC News Online
Mystery still surrounds the intended use of explosives found on board a ship, seized off the Greek coast
Greece has described the 640 ton cargo - which was bound for Sudan - as similar to "an atomic bomb".
But the Sudanese Government has criticised the seizure and backed claims by a Khartoum-based company that the explosives were destined for cement factories and road-building firms.
Documents from the ship described the cargo as Anfo, an explosive made by mixing ammonium nitrate with fuel oil.
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But explosives experts have told BBC News Online that shipping any Anfo at all was a highly unusual move.
"It is a homemade explosive, and not something normally sold as mixed," said Garth Whitty, a former weapons inspector and now head of the Homeland Security department of the Royal United Services Institute.
"There would be nothing suspicious about shipping 680 ton of ammonium nitrate but why ship that amount of Anfo when it is easily mixed on site?"
Anfo is not difficult to make and its main ingredients, ammonium nitrate and fuel oil, are cheap and relatively easy to acquire.
Commonly used for mining and quarrying, it also became a favourite of terrorist groups and was used in bomb attacks carried out by IRA groups.
"A recent car bomb found in Northern Ireland carried around half a ton of explosive similar to Anfo which would have caused a very significant blast had it detonated," said Dr John Wright, an ex-Ministry of Defence scientist and explosives expert.
"The amount on the boat is a great deal indeed. If it is to be used for quarrying then the quantity would not be so surprising. If it is for terrorists, they could do a large amount of damage".
He said the size of the ammonium nitrate particles would held to indicate whether its purpose was for a large, quicker explosion, such as a bomb, or a less violent blast, for say quarrying.
Mr Whitty said the way the explosive had been stored on the ship would also be a tell-tale sign.
"If it has all been poured in a hold, close to detonators and booster chargers, then the ship itself could be used as the bomb," he said.
"If the explosive has been carefully stored in containers, properly marked and away from detonators then it is probably legitimate."