GENEVA, Dec 6 (Reuters) - The United States on Tuesday urged delaying a decision on whether to waive patent protection for COVID-19 treatments and tests, as demanded by many developing countries, a move branded "pathetic" by a leading campaign group.

World Trade Organization members agreed in June a partial waiver of intellectual property (IP) rights for COVID-19 vaccines, with an understanding that they should consider within six months extending this to therapeutics and diagnostics.

India, South Africa and other developing countries have been pushing for a waiver extension, which many developed countries argue could discourage the pharmaceutical industry from responding rapidly to future global health crises.

The office of the United States Trade Representative said in a statement that it supported delaying the deadline and that it would ask the U.S. International Trade Commission (USITC) to launch an investigation into the products at issue.

"Real questions remain on a range of issues, and the additional time, coupled with information from the USITC, will help the world make a more informed decision," U.S. Trade Representative Katharine Tai said in a statement.

She said the aim was to determine if extending the waiver would result in increased access to the products.

Campaign group People's Vaccine Alliance said an USITC investigation can take nine months to a year to complete.

"The U.S. has had more than two years to meaningfully engage in WTO negotiations over access to lifesaving tests and treatments. Kicking the issue further into the long grass, just as the negotiating deadline approaches, is pathetic," policy co-leader Mohga Kamal-Yanni said in a statement.

The deadline for a decision has been Dec. 17, but there has been an unresolved stand-off on the issue at the WTO.

A trade delegate involved with the talks said WTO Director-General Ngozi Okonjo-Iweala had called a stock-taking meeting of several key countries, including the United States, on Tuesday. (Reporting by Philip Blenkinsop, Emma Farge and Washington newsroom; Editing by Bernadette Baum and Catherine Evans)