Civil Defence is developing a plan to allow business owners controlled access to buildings within the CBD red zone to enable them to recover business records, stock and other possessions.

A three-day moratorium on demolition work in the earthquake-damaged city's CBD has been in place since yesterday, with only urgent work to take down structures blocking access to other buildings taking place.

Civil Defence national controller John Hamilton indicated today the earthquake response was moving from the urgent phase to focusing on structured recovery.

Access was likely to be arranged building by building, and for small groups at a time accompanied by engineers and Urban Search and Rescue (USAR) crew to ensure their safety, he said.

This would enable businesses to retrieve essential items so they could operate from alternative premises.

The plans were being developed in conjunction with the Chamber of Commerce and the Canterbury Business Recovery Group.

Mr Hamilton said he had approved demolition, deconstruction or dismantling of 139 buildings within the CBD. In 17 cases it had been done without prior contact with building owners because it had proved impossible to reach them.

More than 180 people are believed to have died in the quake which struck on February 22.

Yesterday they were remembered at a national memorial service in the city's Hagley Park, which was attended by thousands, including Prince William, who has since left to visit flood-damaged parts of Australia.