Specialist search and rescue teams from overseas are helping in the search for survivors of the devastating earthquake in Christchurch.

Search efforts have been boosted by the arrival of experts from the UK, United States, Japan, Singapore and Taiwan. Many of those personnel will focus on grid searches in the suburbs outside the city.

Australia has provided 140 search and rescue personnel.

A 75-bed army field hospital is due to arrive from Australia in Christchurch this afternoon.

The field hospital will be staffed by 25 Australian clinicians including six emergency department doctors and 13 nurses, the Canterbury District Health Board said.

Eighty seven search and rescue workers from Singapore, and 116 Singaporean defence forces are already in the city as are 24 personnel from Taiwan.

More than 60 specialist search and rescue volunteers from the UK will also arrive today.

An 80-strong Disaster Assistance Response Team arrived from the United States this morning, with Japanese general medical and rescue workers arriving later in the day.

The Japanese team of 63 people, will be focusing on the Canterbury TV building in the CBD, where many are unlikely to have survived.