Harare - The body found on board a US-registered plane that has been impounded in Zimbabwe was in an advanced stage of decomposition, it was reported on Tuesday.

Zimbabwean authorities have requested help from Interpol as they probe the mystery of the body, found on Sunday on board a plane transporting millions of South African rands to Durban, which were apparently printed in Germany, says the official Herald newspaper.

The black male adult is understood to have been dead for some time and it is not clear whether he was a stowaway or whether he died due to conditions on the plane, according to tweets from Chris Chivinge of the state Zimbabwe Broadcasting Corporation (ZBC).

He has not yet been identified.

The four-member crew, said to include a South African, said they knew nothing about the body, according to ZBC.

They were reportedly being kept in an undisclosed location for security reasons.

There erre no reports of arrests so far.

On Monday, Zimbabweans woke up to news that a corpse dripping blood had been found aboard the US-registered plane. 

The aircraft, which had been leased to a British firm by US-based Western Global Airlines, has now been impounded together with its consignment, said to consist of millions in freshly-minted South African rand notes on their way from Munich, Germany, to Durban in KwaZulu-Natal for the South African Reserve Bank.

Zimbabwean officials removed the body of the man from the plane on Monday, placing it inside a metal coffin that was hoisted up to an opening in the plane’s fuselage, according to a picture published in the private NewsDay.

A post-mortem was now being carried out "to establish whether the body is not carrying viruses that may cause the spread of diseases here", the Herald reported.

Earlier reports said that ground staff at Harare International Airport had been alerted to the presence of the body on Sunday by blood dripping from the plane’s air conditioning vault.

The Herald suggested that what had been initially thought to be blood may in fact have been other fluids from the decomposing corpse.