GENEVA (Reuters) - The World Health Organization´s 192 member states on Friday committed themselves to promptly report any human cases of bird flu to build defenses against a possible pandemic.

New international health regulations, due to come into force for all infectious diseases from June 2007, were brought forward by a year on a voluntary basis for bird flu in light of growing concerns about the fast-spreading virus.

Experts fear that the H5N1 strain of bird flu, which has already killed 124 people in ten countries, could trigger a global pandemic if it mutates to pass easily between humans.

The WHO rules, first agreed upon last year, ask countries to disclose any event "that may constitute a public health emergency of international concern". Previous regulations had covered only cholera, plague, yellow fever and smallpox.

Countries are also asked to undertake routine checks at ports, airports and land borders to help detect and respond quickly to public health emergencies.

Margaret Chan, the WHO´s assistant director-general for communicable diseases, said making the rules take effect sooner offered countries "better defense" against health threats that might otherwise spiral out of control.

Anders Nordstom, who took over the helm of the U.N. health agency after Director-General Lee Jong-wook´s sudden death on Monday, said bringing the regulations into force was a "priority both for me and for the organization".

Nordstom said recent attention on new diseases -- sparked by the appearance of SARS in 2003, and bird flu which re-emerged in Asia the same year -- had prompted many countries to apply the standards early.

"In some ways it is already happening, and we expect now with this decision -- which is more of a political commitment -- that we will be able to accelerate even more," he told his first news conference as the United Nations agency´s interim chief.

Though bird flu remains principally an animal disease, its H5N1 strain has infected 213 people, killing more than half of them, since 2003. More than 30 countries have reported outbreaks in wild birds or poultry since the start of this year.

(Additional reporting by Stephanie Nebehay in Geneva)