N'DJAMENA (AFP) -- The United Nations Monday condemned an attack on an aid worker in Chad which left her seriously injured and warned of growing lawlessness in the central African country.

A statement said that in the eastern town of Abeche on Friday a staff member of the UN Children's Fund UNICEF, driving a clearly-marked UNICEF vehicle, was shot twice at close range by a man in military uniform.

The incident took place in front of the residence of the international aid agency Oxfam. The victim was thrown from the car by the gunman, who then drove off with the UNICEF vehicle.

"Hearing the gunfire, colleagues from Oxfam rushed the victim to the French military base in Abeche, where she received emergency treatment before being evacuated to the capital, N'Djamena, in critical condition," the statement said.

She has since been evacuated to Paris for intensive care.

"The United Nations in Chad also laments the fact that this is the 24th case of carjacking of a humanitarian vehicle in the country and that, until now, no one has been arrested or punished despite the best efforts of authorities," the UN said.

"The deterioration of the security situation has begun to seriously affect humanitarian operations in eastern Chad, and has become all the more worrisome in light of the impunity with which such criminality continues to take place. "Given the growing state of insecurity, the United Nations in Chad calls on Chadian authorities to take the measures necessary to ensure the safety of all civilians, including those of the humanitarian community."

Chad is experiencing increasing unrest fuelled by attempts to topple President Idriss Deby Itno being mounted by rebels based in the east of the country and neighboring Sudan.