The US Coastguard says a report of a yacht - possibly with a Kiwi crewman - being blown up and sunk could be a hoax.

Maritime NZ won't reveal details of how the $37 million Rena clean-up bill has been spent.

The container ship captain responsible for NZ's worst environmental maritime disaster tried to cover up shoddy seamanship by ordering records to be changed - and then kept quiet about it.