A sword attack victim spent most of yesterday having surgery to reattach his hands.

The 20-year-old was attacked by a man wielding what was thought to be a samurai sword outside a party in Linton St, in Palmerston North on Saturday night.

Detective Senior Sergeant Craig Sheridan told NZPA the man was still in a serious condition in Hutt Hospital and it would be some days before he could be interviewed.

The victim had one hand almost completely severed and the other hand badly damaged in the attack.

It is not yet known if the surgery will be successful.

Mr Sheridan said the inquiry team had a big task ahead as they worked through interviews with a number of people who may have useful information.

"Yesterday we interviewed in excess of 12 people and we've got a whole lot more to do today and in the days ahead."

Mr Sheridan said Linton St was a busy road and he had "absolutely no idea" how many people may have been in the area at the time, in addition to the partygoers.

Police knew the attacker was not associated with the party or the address where the victim lived, he said.