The Malaysian government cleared on Saturday three people suspected of contracting a deadly bird flu virus but admitted another person to hospital for checks.
Health officials are screening hundreds of people living in a village near the Thai border after two chickens there were found with the deadly H5N1 strain of avian influenza.
The World Health Organisation fears the H5N1 virus, blamed for 27 deaths in Asia this year, could mutate into a highly contagious form which will trigger the next flu pandemic.
Tests on the three people initially quarantined in hospital with cold symptoms - two villagers and a veterinary worker sent to the scene of the outbreak - showed they had not contracted bird flu, deputy director general of health Shafie Ooyub said.
"One of them had normal fever and the others did not have fever," he told reporters.
But Health Minister Chua Soi Lek said a veterinarian from another part of the same northern state of Kelantan had been admitted to hospital for checks.
"She complained of having fever and flu. The vet's neighbour raises chickens," Chua told reporters.
Malaysia, accused this week of putting pressure on the domestic media not to report its first outbreak of bird flu, pledged on Saturday to be open with its people.
"Of course we'll be completely transparent. There's no question of that," Prime Minister Abdullah Ahmad Badawi told Reuters.
Disease outbreaks have frequently led to charges of cover-ups, as governments from China to Britain have struggled to balance public safety with business and political interests and a fear of public hysteria.
Malaysian news agency Bernama reported on Wednesday the government had directed media not to report the "so-called bird flu outbreak".
Government officials denied issuing any such instruction but media sources said editors had been told to play down the story out of fear of public panic.
China was heavily criticised last year for covering up the early spread of Severe Acute Respiratory Syndrome and Thailand faced similar accusations this year when it initially blamed a bird flu outbreak on a stock disease humans cannot catch.
British scientists accused their government of covering up for 10 years the risk to humans from mad cow disease, now blamed for the deaths of more than 80 people since it surfaced in 1985.
The WHO called on Saturday for more information from China after a scientist there said bird flu had been found in pigs. Influenza viruses have in the past jumped from birds to pigs, and then to humans.
Malaysian poultry farmers, banned from selling eggs and poultry in their key export market of Singapore, face losses of up to $790,000 a day.