Magdi Salih, the head of the epidemics department, said on Tuesday that tests carried out by Sudanese authorities on the man and chickens had proved positive for bird flu, but he did not say if the virus was the deadly H5N1 strain.

The infected chickens were found at two farms in Sudan's Khartoum and Jazeera provinces, one of which belonged to the infected man.

Samples would be sent abroad for further tests, Salih said.

The World Health Organisation (WHO) said it was looking into the report.

"We don't have a lot of details as to what kinds of tests were done, but we are obviously keen to have the samples sent abroad," spokeswoman Maria Cheng said.

The H5N1 strain of bird flu has been confirmed in neighbouring Egypt, which has reported four human deaths from the virus.

Bird flu has killed at least 109 people in nine countries, according to the most recent WHO figures.

The virus remains essentially an animal disease, but there are fears it could mutate into a form which passes easily among people, sparking a pandemic in which millions could die.

China's 17th case

Meanwhile, China reported its 17th human case of the H5N1 strain of bird flu since November in a 21-year-old security guard from the central city of Wuhan, the WHO said.

The man was confirmed on Tuesday to have the virus, but the source of his exposure is still under investigation, said Aphaluck Bhatiasevi, a spokeswoman for the WHO's Beijing office.

He became sick on April 1 and was hospitalised in critical condition with a high fever, she said.

Eleven people in China have died from the disease.