Laura Archer is pictured in this undated handout photo in Sudan. The Montreal nurse is among three Médecins Sans Frontières workers abducted in Darfur Wednesday. (MSF/Canadian Press)Abductors holding a Canadian nurse and two other employees of the Belgian branch of Médecins Sans Frontières in Sudan's Darfur region are demanding a ransom, according to Sudanese media.

No further details were available.

The general director of the Canadian arm of Médecins Sans Frontières (Doctors Without Borders) told reporters that Laura Archer, a nurse who was living in Montreal before leaving for Darfur, was one of those abducted.

Marilyn McHarg, speaking at a Thursday news conference in Toronto, said the abduction was "very much unexpected."

"There has not been an abduction like this in Darfur before," she said.

Mauro D’Ascanio, an Italian doctor, and Raphaël Meunier, a French field co-ordinator were also abducted, Médecins Sans Frontières said in a statement. Two Sudanese employees were also taken but were soon released, the group said.

McHarg said no group has taken responsibility and that her organization has not had any contact with the abductors, who were reportedly armed.

However, there was a phone call from the kidnapped staff Wednesday night, she added.

"When we had the contact it was between the team in the area and the staff who had been abducted and we did get confirmation that they were OK, they were in good health, they were together and that they were being well-treated."

Archer's family was concerned about the situation, but was very strong and stoic, she said.

"Our concern is for the safety of those that have been abducted and we're hoping for a very swift and safe release," she said.

The next steps are to "keep the lines open" to be ready for negotiation and to co-ordinate with the Sudanese and the Canadian governments, said McHarg.

Susan Sandars, a spokesperson for the group in Nairobi, Kenya, said she had no information on the motive for the abduction or the whereabouts of the aid workers.

Noureddine Mezni, a spokesman for United Nations peacekeepers in Khartoum, said the abductions took place Wednesday in Serif Umra, North Darfur, about 205 kilometres from the town of El Fasher.

The Sudanese Foreign Ministry later issued a statement that said, "The available information up to now indicates that all those kidnapped are in good health and have not been harmed."

Friends shocked by abduction

Archer, a graduate of the University of Prince Edward Island, had previously worked with Médecins Sans Frontières in the Central African Republic, Chad and Congo. According to a website featuring paintings of people she encountered while working in Africa, she was due to return from Darfur next month.

Archer's friends and neighbours in Montreal were shocked to hear about her abduction. At the café across from her loft in Montreal's St-Henri district, patrons and staff described her as a strong-willed woman who was well aware of the risks of working in Darfur.

Archer was employed at the café as a dishwasher in the past. Her artwork, depicting images from her travels with MSF, often hung on the café's walls.

Jonathan MacLeod, who works at the café, grew up with Archer in Charlottetown. He said if anyone could cope with the stress of a hostage situation, it would be his friend.

Group recalling all remaining staff

Earlier Thursday, Christopher Stokes, director of Médecins Sans Frontières Belgium, said in Brussels that the group decided to pull out its remaining staff from Darfur to Khartoum as a safety precaution until those abducted are freed.

Médecins Sans Frontières director of operations Stephan Goetghebuer, left, speaks during a media conference in Brussels on Thursday. Seated right is general director Christopher Stokes. (Virginia Mayo/Associated Press)"We are trying to negotiate for the moment the release of our colleagues," Stokes said. "The only people that will stay behind are the people dealing with trying to secure the freedom of our colleagues. The remaining ... MSF Belgium, Switzerland and Spain ... also decided to withdraw their teams."

Wednesday's abductions come a week after Sudanese President Omar al-Bashir expelled 13 aid groups — including sections of Médecins Sans Frontières — from his country, following a warrant issued for his arrest by the International Criminal Court on charges of war crimes and crimes against humanity.

French and Dutch arms of Médecins Sans Frontières in Darfur have been expelled, the aid group said, but the Belgian, Swiss and Spanish branches in the region are not affected.

The UN has said the expulsions would severely impact the lives of two million people in Darfur, as nearly 40 per cent of the aid workers there were affected by the decision.

Al-Bashir accused the aid groups of undermining security in Sudan and of conspiring with the ICC.

"MSF has never collaborated with the ICC," Stephan Goetghebuer, the director of the Belgian arm of Médecins Sans Frontières, told the Reuters news agency. "Yet, it's obvious that part of the population in Sudan took these accusations about [non-governmental organizations] very seriously."

He told Reuters that his group was subject to increased antagonism after the ICC issued the arrest warrant.

The UN estimates that more than 300,000 people have been killed and 2.5 million forced from their homes since 2003 by fighting between tribal rebels and militiamen said to be backed by the Arab-dominated regime.

With files from the Associated Press