WASHINGTON — Defense Secretary Leon E. Panetta is lifting the military’s official ban on women in combat, which will open up hundreds of thousands of additional front-line jobs to them, senior defense officials said Wednesday.

The groundbreaking decision overturns a 1994 Pentagon rule that restricts women from artillery, armor, infantry and other such combat roles, even though in reality women have frequently found themselves in combat in Iraq and Afghanistan; according to the Pentagon, hundreds of thousands of women have deployed in those conflicts. As of last year, more than 800 women had been wounded in the two wars and more than 130 had died.

Defense officials offered few details about Mr. Panetta’s decision but described it as the beginning of a process to allow the branches of the military to put the change into effect. Defense officials said Mr. Panetta had made the decision on the recommendation of the Joint Chiefs of Staff.

Women have long chafed under the combat restrictions and have increasingly pressured the Pentagon to catch up with the reality on the battlefield. The move comes as Mr. Panetta is about to step down from his post and would leave him with a major legacy after only 18 months in the job.