New Zealand authorities warned Sunday the state of emergency in quake-hit Christchurch may be extended despite the aftershocks becoming less frequent and weaker.

The warning came as local members of the triumphant All Blacks rugby team were drafted in to put a positive face on a trauma campaign a week after a powerful 7.0 earthquake brought havoc to the city.

Civil defence officials said the number of people using welfare centres has stabilised, the majority of public services were operating and the water supply to most areas was deemed safe.

Electricity has been restored to most areas, all hospitals are fully operational, and most schools intend to open on Monday.

The number of daily aftershocks peaked at 98 the day after the huge earthquake but had dwindled to fewer than 20 a week later.

But regional civil defence controller John Mitchell said the state of emergency, which has already been extended to midday Wednesday (0000 GMT), will not be lifted until all emergency services are satisfied.

Christchurch members of the All Blacks side who beat the Wallabies 23-22 in Sydney on Saturday to complete a clean sweep of the Tri-Nations championship, were due home Sunday to help with an earthquake trauma campaign.

Captain Richie McCaw, Kieran Read, Brad Thorn and Corey Flynn will be involved in advertisements urging people traumatised by the quake and aftershocks not to be reluctant to seek psychological help.

Flynn said they were looking forward to getting home as they departed for Sydney a day after the quake hit and before the full extent of damage was apparent.

"We want to get back, make sure everything's all right, make sure the house is in order, the family' good and then we'll go for there," he said.

About 500 people attended a multi-denominational church service on Sunday held outdoors in the centre of Christchurch after the earthquake and aftershocks damaged several churches in the region.

Cathedral dean Peter Beck told the nzherald.co.nz website the service had been well-received in the community.

"People, once they've known about it in the last few days, have been saying: 'Really glad. Time to come into the heart of the city and to say this city's heart is strong. We're all strong and resolute in the midst of this tragedy that we've all been through'," he said.

Mayor Bob Parker told Newstalk ZB radio that moral support would become increasingly important as the media glare shifted from his city.

"Ongoing moral support is probably one of the most positive things people can do for us down here," he said.

Insurance claims from the earthquake are expected to reach two billion dollars and the government expected payments on initial claims would start over the next week.

Earthquake Recovery Minister Gerry Brownlee said he had been in talks with insurers, banks and local authorities about getting people paid and repairs carried out.

The earthquake commission said it had received 44,000 claims from home owners in the first week after the quake.