The mayor of Christchurch offered a formal apology on Sunday to families, including from Japan, who lost loved ones in the collapse of a six-story building in a 2011 earthquake.

Mayor Lianne Dalziel, who took office in 2013, met privately with the families in the central New Zealand city's Arts Centre to convey the apology.

Of the 185 people across the city who died in the magnitude 6.3 earthquake, 115 were in the Canterbury Television Building which crumbled to the ground in seconds, including 28 Japanese students attending an English-language school on the building's third floor.

Kazuo Horita, whose 19-year-old daughter Megumi died in the building collapse, said after the meeting that he felt as though a weight had been lifted from his shoulders after waiting so long to hear an apology.

(Kazuo (C) and Seiko Horita(L))

"I'm grateful the mayor showed humanity and apologized in person, rather than simply in writing," Horita, 65, said. "I think the mayor understood the importance of apologizing in person."

Together with his wife, Seiko, 60, he has traveled to Christchurch every year to mark the anniversary of Megumi's death.

Other Japanese also traveled to Christchurch to hear the apology at the invitation of the mayor, who wrote to bereaved families late last year.

Dalziel, who is scheduled to travel to Japan to provide a similar apology to bereaved families in Tokyo on Tuesday, refused to comment on the contents of the meeting, saying all communication with the families is private.

(Kikuo (front R) and Chizuko Suzuki (2nd from R))

But Maan Alkaisi, spokesperson for an organization of bereaved families, the CTV Families Group, told reporters that the apology included a recognition by the city council that the building's design was flawed.

"It's an acknowledgement that for us, for the CTV Building in particular, the design was wrong and should not have been permitted," said Alkaisi, who lost his wife in the collapse.

"It's an acknowledgement that something went wrong and (it) is documented now in the history of Christchurch that things should have been done differently and that the city council acknowledges some wrongdoing."

A 2012 inquiry into the collapse found Christchurch City Council should not have provided a building permit as the structure did not meet prevailing standards when it was built in 1986.

Investigations also found council staff who inspected the building following a previous earthquake in September 2010 were not engineers, and should not have deemed it safe to occupy.

(Mayor Lianne Dalziel)

While many bereaved family members who attended Sunday's apology were grateful for the mayor's words, they are still fighting for criminal charges to be brought against the building's engineers.

"Today was an admission that the design of these buildings were wrong, should not have been permitted, but justice and accountability and closure is another chapter that we're still fighting for," Alkaisi said.

In 2017, New Zealand police said they would not pursue a criminal prosecution in relation to the building collapse, citing a lack of evidence to secure a conviction in court.

On Saturday, following a public memorial service for the ninth anniversary of the quake, Alkaisi told Kyodo News that families from Japan have also written to the New Zealand solicitor general questioning the decision not to seek prosecution.

"Families in Japan with families here in New Zealand are essentially trying to communicate all the concerns and worries between us and channel it to the government so that we show that this has not only national but also international significance," he said.

Related coverage:

Couple dreams of revitalizing Fukushima with Jersey milk

Kobe marks quarter-century anniversary of massive quake disaster

Japan defense planes arrive in Australia to help fight bushfires