A desperate night-time search is under way for a woman who fell off a cruise ship in rough seas.

A crew member saw the woman fall off the Pacific Dawn at about 4pm when it was 300km west of Pacific island New Caledonia.

Shocked passengers said they heard crew scream ‘man overboard’ before the ship gradually came to a halt and turned around to find the woman.

Children on board are terrified as the ship battles four-metre swells after crew threw life rings into the Coral Sea.

The area is so remote the 245-metre-long ship has to search alone because other boats cannot get there in time.

The captain has announced the search will continue until midnight, passenger Jonathan Trevithick wrote on Twitter.

He posted an image of a life ring floating in the water and said: ‘Horrendous here on ship…. ship going round and round searching.’

Describing the panic when the woman fell, he added: ‘I was on deck and heard someone cry “man overboard”.

‘The ship ground to a halt which took a while, of course.’ In a later update, he tweeted: ‘Not looking good. Nightfall now. Ship still searching.’

P&O spokesman David Jones said in a statement: ‘A crew member notified the bridge straight away and the ‘man overboard’ incident response was activated immediately.

‘In line with this response, Pacific Dawn turned around to follow the course it was on at the time of the incident.’

The captain has announced the search will continue until midnight, passenger Jonathan Trevithick said on Twitter

The Australian Maritime Safety Bureau and New Caledonian authorities issued a call for nearby vessels to assist in the search – but none were close enough.

A spokesman added: ‘It would take days for anyone to reach the area it’s so remote.’

A Brisbane man holidaying on the ship with his family said conditions in the search area are rough, with three to four-metre swells.

He said little information was being given to passengers about the situation other than that they were searching for the missing woman.

The ship was on a week-long cruise of Pacific islands, leaving Brisbane last Saturday where it will return in two days’ time.

Pacific Dawn is 245 metres long and can accommodate 1,500 passengers on 11 decks.

At least 308 people have gone overboard from cruise ships since 2000.