WASHINGTON — Suicides among U.S. soldiers shot up again last year and is at a nearly three-decade high, senior defense officials said today.

At least 128 soldiers killed themselves in 2008, said two officials, who spoke on condition of anonymity because the data has not been formally released.

The final count likely will be considerably higher because more than a dozen other suspicious deaths are still being investigated and could also turn out to be self-inflicted.

The new figure of more than 128 compares to 115 in 2007 and 102 in 2006. It is the highest since record keeping began in 1980.

It also calculates to a rate of 20.2 per 100,000 soldiers, which is higher than the adjusted civilian rate for the first time since the Vietnam War, officials said.

The Army plans to announce figures at a news conference later today.

Officials have said repeatedly said that troops are under tremendous and unprecedented stress because of repeated and long tours of duty due to the simultaneous wars in Iraq and Afghanistan.