The U.N. refugee agency says an aerial bombing overnight and Tuesday morning in West Darfur, Sudan, close to the border with Chad, has forced the agency to withdraw its team. The aid workers were caring for newly arrived refugees in the Birak area in Chad, which is close to the insecure border. Lisa Schlein reports for VOA from UNHCR headquarters in Geneva.

The UNHCR says it learned about the attack from seven refugees who crossed the border from West Darfur into Chad Monday evening. It says the refugees were carrying a 55-year-old woman who had lost both her legs during an alleged overnight bombing.

U.N. refugee spokeswoman, Jennifer Pagonis, says the refugees reported the Aro Sharow camp for internally displaced people, north of Jebel Moon in West Darfur, was attacked. She says the woman later died.

"The refugees said more people would now be fleeing to Chad," said Pagonis. "We have no confirmation or further details of the alleged bombing raid but bombings could be heard from Birak.

"This highlights the extremely vulnerable situation of the refugees and of the humanitarian workers who are helping them. For protection and security the refugees need to urgently be moved away from the border. We are still discussing the transfer to existing camps near Guereda with the Chadian authorities," she added. 

A new influx of refugees into eastern Chad began February 8 following deadly attacks by the Sudanese-backed janjaweed militia in West Darfur. Since then, the UNHCR reports about 10,000 Sudanese refugees have arrived in Chad. Aid workers on the ground say more arrivals are expected as well as more displacement in West Darfur because of the bombing.

Last week, the UNHCR tried to move thousands of Sudanese refugees away from the insecure border to safer camps inside Chad, but unarmed gunmen blocked these efforts.

Pagonis says both the refugees and humanitarian workers at the border are in a vulnerable situation.

"There are unknown, armed men roaming around this area," said Pagonis. "We do not necessarily know who these people are. We have called on the government of Chad to provide more security for humanitarian workers. It is a difficult situation for everybody. And, this is now being complicated by having the situation where we have heard of these bombings this morning."

Pagonis says the aid workers who were forced to leave Birak will return as soon as the situation calms down.

In the meantime, on the Chadian side of the border, the UNHCR Spokeswoman says humanitarian organizations have carried out a one-off distribution of supplies to the refugees who are waiting to be transferred to camps further inland. These include blankets, plastic sheets, jerrycans, mats and soap.

She says high-energy plumpynut supplies were given for malnourished children. She says water supply is difficult at the border and some refugees have to walk several hours a day to find water.