By Jennifer Rigby

LONDON (Reuters) -The World Health Organization is pushing countries to raise the prices of sugary drinks, alcohol and tobacco by 50% over the next 10 years through taxation, its strongest backing yet for taxes to help tackle chronic public health problems.

The United Nations health agency said the move would help cut consumption of the products, which contribute to diseases like diabetes and some cancers, as well as raising money at a time when development aid is shrinking and public debt rising.

"Health taxes are one of the most efficient tools we have," said Jeremy Farrar, WHO assistant-director general of health promotion and disease prevention and control. "It's time to act."

The WHO launched the push, which it is called "3 by 35" at the UN Finance for Development conference in Seville.

WHO said that its tax initiative could raise $1 trillion by 2035 based on evidence from health taxes in countries such as Colombia and South Africa.

The WHO has backed tobacco taxes and price rises for decades, and has called for taxes on alcohol and sugary drinks in recent years, but this is the first time it has suggested a target price rise for all three products.

WHO Director-General Dr Tedros Adhanom Ghebreyesus told the conference that the taxes could help governments "adjust to the new reality" and bolster their own health systems with the money raised.

Many low and middle-income countries are coping with cuts to aid spending led by the United States, which is not attending the Seville conference. The U.S. is also in the process of withdrawing from the WHO.

FROM $4 to $10

As an example, the initiative would mean a government in a middle-income country raising taxes on the product to push the price up from $4 today to $10 by 2035, taking into account inflation, said WHO health economist Guillermo Sandoval.

Nearly 140 countries had already raised tobacco taxes and therefore prices by over 50% on average between 2012 and 2022, the WHO added.

Sandoval said the WHO was also considering broader taxation recommendations, including on ultra-processed food, after the agency finalises its definition of that type of food in the coming months. But he added that the agency expected pushback from the industries involved.

The initiative is also backed by Bloomberg Philanthropies, the World Bank and the Organization for Economic Co-operation and Development (OECD), and involves support for countries who want to take action.

(Reporting by Jennifer Rigby and Virginia Furness; editing by David Evans)