CHRISTCHURCH, New Zealand - Grieving New Zealanders prayed in the earthquake-ravaged city of Christchurch on Sunday as rescuers pulled apart leveled buildings in their desperate search for survivors six days after the devastating tremor that killed 147 people.

Rescue teams from New Zealand and seven countries, including the United States, China, Japan, and Australia, scoured ruined buildings in the central city and suburban areas hardest hit by Tuesday's 6.3 tremor - but found only the dead.

"They can see bodies that they are trying to get out," police shift commander Russell Gibson said.

The dead include people from 20 nations, including dozens of students from Japan and China who were in Christchurch, one of New Zealand's most attractive cities, to learn English in view of the country's dramatic southern Alps.

The city's mayor clung to the hope that more would be found alive, even as aftershocks brought down masonry and sent rescue teams scrambling for safety.

"I will not stop hoping that we will find people alive in the damaged structures of our city until I am told by the police and the urban search and rescue teams that no such optimism can exist any longer," Bob Parker told reporters.

No survivors have been rescued since mid-afternoon on Wednesday. The number of missing remains at more than 200, but police have said it is likely that the number includes recovered bodies that have yet to be identified. In the central city, the painstaking search concentrated on a finance company office block, the city's landmark cathedral and a local television building, which housed an English language school.

Japanese, Chinese and English teams joined locals to pull apart the buildings, where floors pancaked on top of each other, brick by brick. As of Sunday, 23 Chinese nationals were still missing, according to Xinhua News Agency.

"What we're doing is removing the debris, we're looking for voids or spaces where there may be the living," said fire rescue head Jim Stuart Black.

Rescuers crawled through large steel tubes to get into the core of the cathedral, where around 20 bodies are believed trapped.

At the historic 155-year-old stone-built Holy Trinity Anglican Church on the fringes of the devastated city center, Reverend Hugh Bowron said parishioners at the first service since the quake were still stunned.

"The church was badly damaged in the last earthquake, and won't be repairable now, so the sense of hope has taken on a much grittier edge'" Bowron said.

Reuters