(Adds details)

By Phil Stewart

WASHINGTON, Jan 17 (Reuters) - The Pentagon said on Friday there had been no effort to play down or delay the release of information on concussive injuries from Iran's Jan. 8 attack on a base hosting U.S. forces in Iraq, saying the public learned just hours after the defense secretary.

U.S. President Donald Trump, Defense Secretary Mark Esper and others throughout the U.S. government for a week had said that Iran's attack on bases in Iraq, in retaliation for the killing of a Iranian general, had not killed or injured any U.S. servicemembers.

That is no longer true, the Pentagon now acknowledges. But U.S. military leadership in Washington only became aware on Thursday that 11 U.S. service members were flown out of Iraq due to concussive symptoms, Pentagon spokesman Jonathan Hoffman said.

"This idea that there was an effort to de-emphasize injuries for some sort of amorphous political agenda doesn't hold water," Hoffman said.

But the disclosure of the concussive symptoms late on Thursday, more than a week after the attack itself, is likely at a minimum to open a debate about the Pentagon's longstanding treatment of brain injury as a different class of wounds that it says do not require immediate reporting up the chain of command.

U.S. military has to immediately report incidents threatening life, limb or eyesight. But suspected brain injury, which can take time to manifest and diagnose, does not have that urgent requirement.

Esper was only informed on Thursday that the service members were flown out of Iraq to receive additional screening and treatment in bases in Kuwait and Germany, the Pentagon said.

The first U.S. service member was flown out of Iraq on Jan. 10 for further evaluation, while others were flown out on Jan. 15.

"They were under their own power, on aircraft and on their way," Hoffman said.

He noted that top Pentagon officials have not sought to minimize Iran's attack and instead repeatedly said Iran tried to kill U.S. troops when it fired 16 short-range ballistic missiles at two Iraqi bases from at least three locations inside Iran.

In his first Friday prayers sermon in eight years, Iran's supreme leader, Ayatollah Ali Khamenei, told worshippers chanting "Death to America" that the elite Guards could take their fight beyond Iran's borders after the U.S. killing of a top Iranian commander. (Reporting by Phil Stewart Editing by Chizu Nomiyama and Alistair Bell)

Our Standards: The Thomson Reuters Trust Principles.