BRUSSELS: Leaders of the world's largest economies back "voluntary licensing" of Covid-19 vaccine patents, the draft conclusions of a summit show, watering down a US push for waivers and earlier commitments to supply more funds to the World Health Organization.

The draft document, seen by Reuters, lists commitments of G20 nations and other countries and is to be adopted on Friday at a Global Health Summit in Rome, one of this year's major events to coordinate global actions against the pandemic.

The draft, which is still subject to changes, is the result of a compromise among experts from G20 nations which remain divided over the waiving of intellectual property rights for Covid-19 vaccines.

The Biden administration earlier in May joined India, South Africa and many other developing countries in calling for a temporary waiver of patents for COVID-19 vaccines, in the hope that it would boost production and allow a fairer distribution of shots across the world.

But the European Union and other vaccine-making countries have raised doubts, saying that the removal of U.S. export restrictions on vaccine raw materials, the transfer of know-how and voluntary cooperation among vaccine makers would ensure a much quicker ramping up of global production.

The health summit's draft conclusions reflect these differing views and make no mention of patent waivers.

G20 leaders are to commit instead to "patent-pooling" which is a less radical measure to encourage the sharing of patents. It is still an "unfriendly" move for pharmaceutical companies, an industry expert said, but far less extreme than a patent waiver.