LONDON, June 1 (Reuters) - Talks aimed at reaching a global agreement on how to better fight pandemics will be concluded by 2025 or earlier if possible, the World Health Organization said on Saturday.

The WHO's 194 member states have been negotiating for two years on an agreement that could increase collaboration before and during pandemics after the acknowledged failures during COVID-19.

The UN-agency had initially aimed for an agreement this week, but talks have been extended amid deep divisions between rich and poorer countries on issues like vaccine-sharing and preparedness.

Countries did, however, reach a parallel deal to update existing legally-binding health rules, known as the International Health Regulations (IHR), which includes a new category of "pandemic emergency" for the most significant and globally threatening health crises.

"The historic decisions taken today demonstrate a common desire by member states to protect their own people, and the world's, from the shared risk of public health emergencies and future pandemics," WHO Director-General Tedros Adhanom Ghebreyesus said in a statement.

"With this agreement, we take steps to hold countries accountable and strengthen measures to stop outbreaks before they threaten Americans and our security,” said U.S. Health and Human Services Secretary Xavier Becerra on Saturday.

The changes to the global health rules were aimed at shoring up the world's defences against new pathogens after COVID-19 killed more than 7 million people, according to WHO data.