WASHINGTON — Officials from the United States Central Command altered intelligence reports to portray a more optimistic picture of the war against the Islamic State in Iraq and Syria than events on the ground warranted, a congressional panel said in a report issued Thursday.

The interim report, from a task force established by the Republican chairmen of the House Armed Services Committee, Intelligence Committee and Defense Appropriations Subcommittee, found “widespread dissatisfaction” among Central Command intelligence analysts, who said superiors were doctoring their assessments of American efforts to defeat the Islamic State. Central Command, known as Centcom, is the military headquarters in Tampa, Fla., that oversees American military operations across the Middle East and Central Asia.

“Intelligence products approved by senior Centcom leaders typically provided a more positive depiction of U.S. antiterrorism efforts than was warranted by facts on the ground and were consistently more positive than analysis produced by other elements of the intelligence community,” a news release about the report said.

“What happened at Centcom is unacceptable — our war fighters suffer when bad analysis is presented to senior policy makers,” said Representative Ken Calvert, Republican of California. “The leadership failures at Centcom reach to the very top of the organization.”