The abductions Tuesday and Wednesday dealt a major blow to attempts to control criminal violence that has threatened disaster response efforts in Port-au-Prince.

Dr Workens Alexandre, who was seized, was among the country's few orthopedic surgeons, desperately needed for quake victims with broken limbs.

An official at the Bernard Mevs Hospital said 45 of the 48 quake victims being treated at the facility needed orthopedic surgery.

Gangs in the rough Martissant neighbourhood on the capital's outskirts had announced a truce earlier in the week to allow aid efforts to through to the the southwestern part of Haiti, which has hit hardest by Saturday's earthquake.

It was unclear if those gangs were involved in the latest abductions, but the founder of the DASH network of affordable hospitals, Dr Ronald La Roche, said criminals have engaged in kidnappings far beyond Martissant.

The Tuesday kidnapping of another doctor, an obstetrician who was on his way to perform an emergency Caesarean delivery, occurred in Petionville, long considered one of the safer and wealthier areas of the capital. The doctor's patient and her child both died due to the delay in treatment.

"We are furious at these people," La Roche said of the kidnappers. "They are responsible for the death of this woman and her child."

Of the supposed truce with gangs in Martisan, he said "we cannot depend on that."

"We feel that the gangsters are getting more daring. They are working now in Petionville, the centre of the city," said La Roche, whose network of eight hospital and clinics will close to non-emergency cases to protest the kidnapping.

The DASH hospitals are treating 27 earthquake victims, and they - and any emergency cases - will continue to receive care.

Kidnappers have contacted the families of both doctors, but there is no information on ransom demands.

The official at the Bernard Mevs Hospital, who asked not to be identified because of safety concerns, said the problem has gotten so bad that a program has been set up so that doctors can stay in hospital rooms for two or three days to avoid the risk of travel.

The quake has killed nearly 2,200 people and injured over 12,000. The abductions in Port-au- Prince directly affect the transfer of patients from the overwhelmed hospitals in the south to the capital, the last hope for the most severely injured.

Prime Minister Ariel Henri, himself the former head of neurosurgery at Bernard Mevs Hospital, had already recognised that the government cannot depend on the gang truce.

"I have already given orders that for travelling from Port-au-Prince to the south, security be provided on the route from Martisan to the worst hit areas," he said.

Australian Associated Press