The DOH is also not disclosing the airport where the patient arrived, and from what province, city or region the patient came from.
DOH officials have also said that President Arroyo is "very concerned" by this development.
Duque also said that contact tracing is already ongoing. The patient's family has been informed and has been asked to perform self-monitoring and quarantine.
"The woman returned with her family who are also being monitored by health authorities," he added.
Duque however clarified that there is no A (H1N1) outbreak in the country and that the government is doing everything to prevent it.
Seven other people are under observation at different Philippine hospitals but laboratory tests have not been completed, the official said.
"We reiterate to the public that the government is on top of the situation and everyone is advised to be vigilant," Duque said.
Some 49 people who had been put under observation in government and private hospitals since May 1 after showing symptoms of the virus have since been discharged, health officials said