The wars in Afghanistan and Pakistan have left nearly 150,000 soldiers and civilians dead since 2001, a new US study estimates.

Another 162,000 have been wounded since the US-led offensive that toppled the Taliban government in Afghanistan after the 9/11 attacks, says the study by the Costs of War Project, based at the Watson Institute for International Studies at Brown University.

The war in Afghanistan is intensifying rather than moving toward an end, it added, as the number of deaths and injuries has increased significantly in recent years.

This, and the United States' announcement this year that it is slowing its troop withdrawal, "underscores the fact that the war in Afghanistan is not ending. It is getting worse," said the study, dated May 22.

In Pakistan, the war has seen a lower intensity in recent years although there remains "very hot conflict" in the northwest of the country.

The study focuses on death and injury caused directly by the stuff of warfare, what it calls "bullets, bombs, fire and so on."

War also causes indirect deaths, as people perish due to malnutrition, lack of health care and the hardship of displacement. But this figure is very hard to tally.

For all the categories of direct fatalities and injured -- soldiers, then civilians including journalists, aid workers and civilian contractors -- the study used sources ranging from US and other allied government figures to the UN aid mission in Afghanistan to data bases of NGOs and think tanks.

Author Neta Crawford said studies on wars since 1990s suggest an "extremely crude rule of thumb" to the effect that for every person who dies a direct death in war, three to 15 die indirectly.

But both countries studied this time have been ravaged by military conflict, and in Afghanistan, torn by decades of war, "there is no peacetime baseline," wrote Crawford, the co-director of the Costs of Wars Program and a professor of political science at Boston University.

So it is nearly impossible to estimate indirect deaths in the two countries, she concluded.

"What we do know is that the indirect health effects of war persist beyond the end of the fighting," Crawford wrote.

"Both Afghanistan and Pakistan will continue to need an infusion of aid for public health after these wars end, a prospect that does not appear imminent."