PHNOM PENH, Cambodia (AP) — Cambodia on Friday reported three new human cases of bird flu, two of them fatal, in the first three weeks of this year. That's as many cases as the Southeast Asian country reported in all of 2012.

The cases are among the first reported in 2013 for the virulent H5N1 virus, which the World Health Organization says has killed 360 other people worldwide since surfacing in 2003.

WHO and Cambodia's health ministry announced that a 15-year-old girl in a village in southeastern Takeo province and a 35-year-old man in central Kampong Speu province died after being hospitalized with H5N1, better known as bird flu. An 8-month-old boy in the capital, Phnom Penh, was treated and survived.

Cambodia reported three cases last year, all of them fatal. Since 2005, it has recorded 21 cases, 19 of them fatal.

The disease remains hard for people to catch, but experts fear it could mutate into a more deadly form that spreads easily from person to person. So far, most human cases have been linked to contact with infected poultry.

On Wednesday, international scientists who last year halted controversial research with the deadly bird flu virus said they were resuming their work as countries adopt new rules to ensure safety.

An outcry had erupted when two labs — in the Netherlands and the U.S. — reported they had created easier-to-spread versions of bird flu. Amid fierce debate about the oversight of such research and whether it might aid terrorists, those scientists voluntarily halted further work last January.

Those scientists announced Wednesday they were ending their moratorium now that health authorities have had time to determine how they will oversee high-stakes research involving dangerous germs. Several countries have already issued new rules.

In letters published in the journals Science and Nature this week, scientists wrote that those who meet their country's requirements have a responsibility to resume studying how the bird flu might mutate to become a bigger threat.