Rena salvors have detected more movement in the bow of the Rena - prompting fears it may be starting to buckle.
Maritime New Zealand spokesperson Sophie Hazelhurst said the increasing movement in the front section of the wreck possibly indicated that another piece could have given way or was beginning to buckle.
But Svitzer spokesman Matt Watson said the increasing movement did not necessarily mean it was imminently expected to give way or topple into the sea any time soon.
However, Mr Watson said since the wreck split in two the structural integrity of the vessel had been seriously compromised and had remained in a "fragile and precarious state" and continued to be closely monitored.
A Bell 214B helicopter - the world's most powerful single-engine helicopter - is being used to remove damaged containers and debris, including large chunks of timber from Bay 12, Row 12 and Bay 86 of the wreck.