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Plans are underway to change the rule that keeps women out of combat.Tetra Images

U.S. Defense Secretary Leon Panetta has decided to lift a ban on women serving in combat, a senior defense official said Wednesday.

Panetta and General Martin Dempsey, the chairman of the US Joint Chiefs of Staff, "are expected to announce the lifting of the direct combat exclusion rule for women in the military," the official, who spoke on condition of anonymity, told reporters.

"This policy change will initiate a process whereby the services will develop plans to implement this decision, which was made by the Secretary of Defense upon the recommendation of the Joint Chiefs of Staff," the official said in an email.

In February last year, Panetta opened up about 14,000 combat-related jobs to female troops for the first time in an incremental move.

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Calls to lift the blanket prohibition have mounted after a decade of war in which women fought and died in counter-insurgency campaigns in Iraq and Afghanistan with no clear front lines.

Some senior officers have privately voiced concerns that infantry and special forces units require major upper body strength and that difficult physical tests should not be relaxed for female recruits.

But some female veterans and activists say they are only demanding an equal chance to apply for combat jobs -- and not any special treatment.

US commanders began taking a second look at the ban in 2010 to reflect the reality on the battlefield, as the wars in Iraq and Afghanistan had thrust women into combat in any case.

The Air Force and Navy have already lifted most prohibitions on women in combat.