WASHINGTON (AP) — International scientists who last year halted controversial research with the deadly bird flu say they are resuming their work as countries adopt new rules to ensure safety.

The outcry 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 — and more than three dozen of the world’s leading flu researchers signed on as well.