The Turkish Health Ministry said on Monday that five people, including a boy who died on Sunday, were tested negative of bird flu in the eastern province of Van, the semi-official Anatolia news agency reported.

Turkish Health Ministry Basic Health Services Director General Turan Buzgan was quoted as saying that the patients' disease did not stem from bird flu or any other influenza virus and efforts were underway to determine the source of the disease.

A seven-member delegation led by Buzgan left for Van for more research, the report said.

A 14-year-old boy, who was tested for possible bird flu together with his brothers and sister, died in a hospital in Van on Sunday. They all showed symptoms of influenza after eating questionable chicken meat.

The ministry released a statement saying that a series of measures have been taken in addition to the measures taken by the Ministry of Agriculture and Rural Affairs, after avian influenza was discovered in poultry in Aralik town in the province of Igdir, near Turkey's far eastern border with Armenia, on Dec. 27, 2005.

According to the statement, nine people who contacted the poultry in Aralik town were medicated as precaution. Quarantine was also imposed in the affected area after some 1,500 dead chicken were tested positive for the H5 variant of bird flu.

On Sunday, Igdir Governor's Office said 756 birds had been culled in the area in order to prevent the spread of the virus.

Experts said migratory birds might have brought the virus to Igdir from the Caucasus region.

An outbreak of bird flu in October 2005 in northwestern Turkey triggered the culling of more than 10,000 birds. The virus was identified as the deadly H5N1 strain that has killed dozens of people in Asia since 2003.