NEW YORK - More civilian contractors working for American companies than US soldiers died in Afghanistan last year for the first time during the ongoing war, according to The New York Times.

The rising number of civilian and contractor deaths could remain an invisible toll of the war since private companies are not required - and often don't - publicly announce the names of their war dead, the newspaper said in a dispatch from Kabul published on Sunday.

Most of the contractors die unheralded and uncounted - and in some cases, leave their survivors uncompensated, the Times said.

"By continuing to outsource high-risk jobs that were previously performed by soldiers, the military, in effect, is privatizing the ultimate sacrifice," Steven Schooner, a law professor at George Washington University who has studied the civilian casualties issue, was quoted as saying.

Last year, at least 430 employees of American contractors were reported killed in Afghanistan, the Times reported, citing compiled data from the American Embassy in Kabul and data publicly available, in part, from the United States Department of Labour.

By comparison, 418 US troops died in Afghanistan, the Times reported, citing figures compiled by an independent group called icasualties.org.

In both Afghanistan and Iraq, the Pentagon routinely relied on civilians and contractors for jobs once performed by military personnel - such as cooks, convoy drivers and personal bodyguards.

With the drawdown of US forces, more and more jobs are likely to be filled by contractors - and experts tell the Times that the true number of private contractor deaths might be far higher.