By David Morgan

WASHINGTON, Sept 6 (Reuters) - The Bush administration is sharply increasing its use of military aid as a reward for countries that cooperate with its war on terrorism, despite concerns about human rights and political instability, researchers said on Thursday.

The Center for Defense Information found large increases in government and commercial U.S. arms sales in recent years to 25 countries in the Middle East, Asia and Africa that have become allies against Islamist militancy since the Sept. 11 attacks.

The nonpartisan Washington-based think tank said half the countries were identified by the State Department in 2006 as having serious, grave or significant human rights problems. Several have weathered serious political turmoil in recent years and some, such as Pakistan, now appear to be unstable.

The list also includes Yemen, Azerbaijan, Thailand, Indonesia, Chad and Mauritania.

The center's analysis of U.S. data showed government-to-government U.S. arms sales to the 25 countries rocketed to $3.9 billion in 2006 from about $400 million a year earlier. The 2006 figure accounted for about 22 percent of the total $18 billion in U.S. foreign military sales last year.

Government projections for 2007 and 2008 call for spending levels well above those recorded from 2001 to 2005, it said.

"The trend is continuing in a steep upward climb," said Rachel Stohl, a co-author of the study.

Officials at the State Department and Pentagon were not immediately available for comment.

In a major initiative this year, Washington announced in July it would funnel military aid worth more than $43 billion to Egypt, Israel, Saudi Arabia and other Gulf states over 10 years to help protect them against Iran and fears of spillover from militant chaos in Iraq.

The package drew criticism that Washington had lost interest in promoting democracy in the region, a goal that it emphasized heavily in the wake of the Sept. 11 attacks.

The Bush administration announced plans earlier this year to sell India military cargo planes and related gear worth up to $1.1 billion in the first major U.S. aircraft deal with New Delhi.

The center also criticized the Bush administration for its increasing use of new military assistance accounts, which it said allow the Pentagon to bypass legal restrictions on training or arming human rights abusers.

"The United States is sending unprecedented levels of military assistance to countries that it simultaneously criticizes for lack of respect for human rights and, in some cases, for questionable democratic processes," the center said in a report posted on its Web site.

"While these countries are currently considered important to U.S. efforts in the 'war on terror' now, political and military instability makes their continued allegiance to the United States questionable."

Military aid increases were due in part to the lifting of sanctions and restrictions against certain countries immediately after Sept. 11, 2001, according to the center.

Direct commercial sales, in which U.S. weapons manufacturers strike deals overseen by the State Department, stood at over $3 billion for the same countries during the period from 2002 through 2006. That was up from $72 million for the five years preceding the Sept. 11 attacks.

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