BANGKOK, June 25 (Reuters) - Laos and the World Health Organization confirmed on Thursday the communist country's first three cases of the H1N1 flu virus, all of them foreigners.

A 9-year-old American boy and an Australian man were recovering after being infected with the virus also known as swine flu, government spokesman Khenthong Nuanthasing said.

Another foreigner, whose nationality was not known, had also contracted the virus and was being treated in hospital in the capital Vientiane, he said.

"The Australian is living in Laos but has fully recovered," he said by telephone. "The other two cases were detected by a scanner when they entered the country at the airport."

The WHO office in Laos confirmed the cases and said all three were recovering.

Neighbouring Cambodia confirmed three more cases on Thursday, all of which were American students. Cambodia reported its first case on Wednesday, a 16-year-old American from the same group.

"All four persons are in a stable condition and recovering well without any complications," Cambodia and the WHO said in a joint statement.

More than 1,000 people have been infected in Thailand, although no deaths have been reported.

As the H1N1 virus has spread around the globe, the WHO has declared an influenza pandemic and advised governments to prepare for a long-term battle against the virus.

There have been more than 56,000 confirmed cases of the H1N1 virus and at least 249 people have died. [ID:nLO89908] (Reporting by Martin Petty; Additional reporting by Ek Madra in Phnom Penh; Editing by Alan Raybould)