The Prime Minister has agreed to meet the families of those killed in the CTV building collapse who are outraged at a police decision not to prosecute over the disaster.

Following a press conference in Christchurch this week, the families said they were seeking legal advice to challenge the decision and were also requesting to sit down with Prime Minister Jacinda Ardern.

In reply, Ms Ardern has confirmed she is happy to meet the families, but could not provide promises of further investigations.

"At this point, I don't want to raise expectations when we are at the beginning of looking at this area but if they wish to meet with me I am more than willing to do that," she told Radio NZ.

Maan Alkaisi, who lost his wife in the collapse, says the police decision is morally and ethically unjustified and wants to see someone held accountable.

"The families will not be silenced by this unfair decision and will continue to stand up for what is right. We will never give up the fight until justice is done," he said.

"(The decision) is simply offensive and undermines the principles and integrity of the New Zealand justice system."

The decision not to lay charges came after a $1.18 million criminal investigation which began in August, 2014.

Police investigated potential charges of negligent manslaughter against two engineers responsible for the CTV building's design in the 1980s.

An engineering report in 2014 identified a number of significant deficiencies in the building's design.

Police said legal advice suggested they were unlikely to get convictions if charges were laid.

The six-storey building collapsed and caught fire after the magnitude 6.3 quake struck in Christchurch on February 22, 2011, killing 115 people inside, including 65 foreign students.

The families will also hold a peaceful protest on Sunday.