(CNN) -- The four Doctors Without Borders staffers abducted earlier this week in Sudan's Darfur region have been "safely released," the group said on Saturday.

Members of the humanitarian group Medecins San Frontieres are greeted at the airport after their release.

Canadian nurse Laura Archer, Italian doctor Mauro D'Ascanio, French coordinator Raphael Meunier and Sudanese watchman Sharif Mohamadin were abducted Wednesday.

They appeared Saturday on Sudanese TV following their release, and the TV news said they had arrived in the city of El-Fasher. They "appear to be OK" and were headed to the Sudanese capital of Khartoum, the aid group said.

Five people were taken in Serif Umra in north Darfur. However, one of them, a Sudanese staffer, was freed earlier. The four work for the Belgian section of Doctors Without Borders, also known as Medicins Sans Frontieres.

"We are incredibly relieved that our colleagues are safe and in good health," said Christopher Stokes, general director of the Belgian section of MSF.

After the abductions the group evacuated virtually all of its international staff from Darfur projects, and Sudanese staffers were relocated. A small team stayed "to secure the release of the kidnapped staff," Doctors Without Borders said.

Stokes stressed the group's outrage over the abductions and said the act illustrates greater dangers for aid workers in Darfur, in western Sudan.

"It is a gross violation of everything that we stand for," Stokes said. "Kidnapping of humanitarian workers jeopardizes humanitarian assistance to the most vulnerable. Our independent medical work must be respected if we are to continue working in conflict areas to save the lives of those who suffer most."

Sudan last week ordered 13 major aid groups to leave the country after the International Criminal Court issued an arrest warrant for President Omar Hassan al-Bashir, accusing him of war crimes and crimes against humanity.

Two of MSF's sections working in Darfur -- one run by the Dutch and one run by the French -- were among those ordered out.

MSF helps people "threatened by violence, neglect, or catastrophe" in more than 60 countries.

The United Nations on Wednesday announced the start of a joint U.N.-Sudanese government mission "to evaluate the need for food, water, health and emergency shelter in Darfur" amid the expulsions of the groups, which are believed to have assisted about 4.7 million people.

The United Nations estimates that 300,000 people have died in Darfur, where government forces and Arab militia allies have been fighting rebels.

People have died "either through direct combat or because of disease, malnutrition or reduced life expectancy." About 3 million people have been displaced since 2003, the U.N. says.

All About Sudan • Darfur