Emergency services worked through the night to rescue dozens of crew from the smouldering and sinking HMNZS Manawanui after it struck the reef off the south coast of Upolu.

Samoan emergency services said a fire rescue team worked "from last night until this morning" to collect and treat the 75 crew members.

"Fortunately, no one was heavily injured and no lives were lost," Samoa Fire and Emergency Services Authority said.

New Zealand Commodore Shane Arndell confirmed that "the 75 crew and passengers on board HMNZS Manawanui have made it to safety in Samoa".

The exact cause of the wreck is not yet known.

The HMNZS Manawanui was used for hydrographic surveys, diving operations and marine salvage and featured a 100-tonne sea crane.

It had been conducting a hydrographic survey one nautical mile from shore in difficult conditions.

Samoan authorities had issued a marine warning for the island's south coast over the weekend.

Winds of up to 40 kilometres (25 miles) per hour and ocean swells of up to four metres (13 feet) were forecast around the time of the incident.

The New Zealand military said rescuers had battled currents and winds that pushed the life rafts and sea boats toward the reefs and "swells made the rescue effort particularly challenging."

The military said it was trying to "understand the implications and minimise the environmental impacts" of the wreckage.

The 85-metre-long ship was built in 2003 and purchased from Norway in 2019.