By Katty Kay
BBC correspondent in Washington
Valuable items missing from the Baghdad Museum were squirreled away in a secret location by the regime of Saddam Hussein in the weeks before the war in Iraq, according to Pentagon officials.
The museum was ransacked by looters
A team of US investigators, which is trying to recover hundreds of missing artefacts from the looted museum, also believes some items may have been hidden in secure vaults in the basement of the Iraqi Central Bank.
It is the stuff of Indiana Jones. Somewhere in Iraq there is a secret storage vault crammed full of ancient jewellery and gold.
The historic valuables were taken from the Baghdad Museum and hidden away in this unknown location just weeks before the war.
But according to the Pentagon, museum staff say they have sworn on the Koran not to reveal its whereabouts until a new Iraqi government is installed in the country.
The US military team investigating the looted museum says the existence of this secret cache, along with two more sealed vaults full of museum artefacts in the basement of the Iraqi Central Bank, makes it harder to know exactly how much is missing.
Colonel Matthew Bogdanos, a burly marine who has suddenly become an expert on Assyrian antiquities, heads a team of 14 US personnel living in the museum compound.
He said records were so poor it could take years even to know what was in the museum in the first place, let along what was stolen by looters.
There was some good news. Colonel Bogdanos said hundreds of archaeological items had already been returned by Iraqi citizens, under a 'no-questions-asked' amnesty.
He insisted recovery was more important than prosecution.
But what Colonel Bogdanos did not answer was why the museum was not better protected in the first place when coalition troops entered the capital.