Police said up to 120 bodies may still lie trapped in the tangled concrete and steel that was the Canterbury Television or CTV building, where dozens of students from Japan, Thailand, China and other Asian countries were believed buried when an English-language school collapsed along with other offices.

"The longer I don't know what happened, the longer my agony becomes," said Rolando Cabunilas, 34, a steel worker from the Philippines whose wife, Ivy Jane, 33, was on her second day of class at the school when the quake struck. She hasn't been heard from since.

"I can't describe it - it's pain, anger, all emotions," he said.

The official death toll from Tuesday's 6.3-magnitude temblor stood at 98, Police Superintendent Dave Cliff said. An additional 226 people were listed as missing, and Prime Minister John Key said there were "grave fears" that many of them did not survive.

AP