GENEVA -- A "toxic combination" of poverty and social injustice is killing people on a grand scale, a World Health Organization (WHO) report said Thursday, urging states to fund healthcare to cut inequalities.

The Commission on the Social Determinants of Health, a report commissioned by the WHO and chaired by Sir Michael Marmot of University College London, said these health inequalities were avoidable but only if concerted efforts were made by governments and civil society.

"Reducing health inequities is an ethical imperative. Social injustice is killing people on a grand scale," the report said.

Marmot told journalists that a girl born in Zambia can expect to live 43 years, while one born in Japan can expect to live twice as long, to 86 years.

"There is no good biological reason why this should be the case," he said, instead pointing the finger at social factors that give rise to such a gaping disparity.

"These health inequalities are preventable. They arise from the circumstances in which people are born, grow, live, work and age -- the social determinants of health," he said.

"Taking action to deal with preventable causes of illness means taking social action... a toxic combination of poor social policies, unfair economic arrangements and bad politics is responsible," he added.

Health care must remain within the public sphere and universally available regardless of people's ability to pay, he said.

"The Commission considers health care a common good, not a market commodity," the report said.

"The Commission advocates financing the health-care system through general taxation and/or mandatory universal insurance ... the evidence is compellingly in favor of a publicly funded health-care system," it added.

Marmot said that whilst "virtually all" high-income countries had such a system, there is no reason why it should be adopted by other countries if governments show the necessary political will and funded healthcare through progressive taxation.

"We are distressed by the reports we see of healthcare simply being unavailable to people because of inability to pay, and we see that throughout lower- and middle-income countries," he said.

The report said it was "unacceptable" that upwards of 100 million people are pushed into poverty each year through "catastrophic" healthcare costs.

The United States is one of the rare developed countries that does not have such a system but relies chiefly on citizens holding private medical insurance.

Marmot said that while it was "not for me to tell one of the richest countries on Earth how it should organize its health care system," the fact that around 49 million Americans do not have health insurance suggests this is not the most efficient model.

"It's not perhaps the best use of money that's being spent. There are a lot of people who feel that, and would actually like to see coming out of the current [presidential] campaign in the US, proposals for a universal health insurance," he said.