Maritime New Zealand has stepped up its response to the oil spill from the container ship Rena after the dispersant applied to the oil slick is proving to be ineffective.

A helicopter spent most of yesterday afternoon spraying Astrolabe Reef, where the ship is stranded, in an effort to disperse the oil slick.

Oil continues to leak from the stranded ship, Rena.

Director of Maritime New Zealand Catherine Taylor has issued the owner of Rena with two notices under section 248 of the Maritime Transport Act 1994 and declared Rena as a hazardous ship.

'This does not put MNZ in charge of the salvage but gives MNZ the ability to take control if MNZ deems it necessary.

'The owner must comply with the directions of the National On Scene Commander (NOSC) and permit him to carry out any inspections necessary to determine what steps need to be taken to control or clean up the area.”

Catherine says they must also establish clear and regular lines of communication with MNZ with regard to the salvage operation both before a plan is put into action and once the operation is underway.

'The vessel owner subsequently appointed the salvage company Svitzer to manage the salvage operation.”

NOSC Rob Service says Svitzer is an internationally recognised and respected company with extensive experience in this type of operation.

He says they already have representatives on board the vessel.

'Rena is still leaking oil. The leak is intermittent and appears to be coming from damaged pipework on the vessel.

'We are not aware of any actual breaches in the fuel tanks. However, because of the extensive damage to the vessel, it's difficult to determine accurately what the scale and scope of the damage is. The crew are working to prevent further leakage.”