LONDON (Reuters) - An investor group managing some $5 trillion said it was pleased with the steps taken by fast-food companies to cut the use of antibiotics in their products and will continue to monitor firms as its three-year-long engagement comes to an end.

Resistance to antibiotics has been flagged as a major risk to public health and economic growth by policymakers and the investor action formed part of global efforts to fight back by curtailing their use in the foodchain.

Since launching its engagement in 2016, the Farm Animal Investment Risk and Return (FAIRR) coalition said it had engaged with 20 companies worth a combined $280 billion.

The companies were asked to establish a policy to phase out routine, non-medical use of antibiotics across their supply chains; specify clear targets and timelines for implementation; and report more transparently on their activities.

All the companies engaged now had a formal policy in place or were expected to release one soon, and some were even outpacing the demands of increasingly tougher local regulations, the report from FAIRR seen by Reuters showed.

While they recognized the need to limit antibiotics use and were working to collect data on usage and supplier compliance with their policies, there remained more to do, it said, with little transparency on implementation, including poor disclosure around antibiotics use and auditing practices.

While formally ending the group engagement, FAIRR said it would continue to track performance and could restart the group effort if companies stall on reform. Individual members of the group may also continue engaging directly with companies.

“FAIRR will be looking at each company’s reporting and disclosure on how they are implementing the policies and commitments they have made. If we see no progress in terms of implementation that could be grounds to re-engage formally,” Jo Raven, engagement manager at FAIRR, told Reuters.

“We also want to explore the issue in other ways. For example FAIRR will be actively looking at the pharmaceutical companies that make antibiotics for animal feed.”