By Mirwais Harooni and Missy Ryan

KABUL, June 20 (Reuters) - U.S. soldiers involved in burning copies of the Koran in Afghanistan may face only administrative discipline, a U.S. official said, a move that could deepen frustration among Afghans seeking more serious punishment for a series of public American missteps there this year.

A U.S. official, speaking on condition of anonymity, said on Wednesday that an investigation into the February incident on a NATO military base near Kabul concluded with recommendations for administrative action for the military personnel involved.

Such action might include a written reprimand or docked pay, but not job loss or criminal charges, the official said. U.S. military officials have not announced any final decisions on the recommendations.

Another U.S. official said the administrative action was recommended for "most of the service members involved" in the incident in which Afghan labourers found charred copies of the Koran among trash on the Bagram base north of Kabul. But the official declined to say exactly how many U.S. troops.

Eleven soldiers were sent out of Afghanistan over the Koran desecration, which U.S. officials said was unintentional but which exposed deep divisions between foreign troops and Afghans wearied by more than 10 years of war.

The office of Afghan President Hamid Karzai declined comment on the possible move by the Pentagon.

Nazir Ahmad Hanafi, an influential member of Afghanistan's parliament and deputy head of its judicial committee, said relatively light punishment for the soldiers involved would have "dangerous consequences."

Hanafi, a member of Afghanistan's Ulema Council of clerics who also took part in an initial joint Afghan-U.S. probe into the incident, said he favoured a more severe punishment, possibly even life in prison.

"Otherwise, it will inflame public opinion," he said.

The Korans were burned after they were removed from a prison library at NATO's largest base in Afghanistan, triggering protests and violence across the country that killed at least 30 people. Shortly afterward, two American officers were shot dead in a secure area of the Afghan Interior Ministry.

Afghanistan initially demanded a public trial for the soldiers involved, while the Taliban urged Afghan forces to turn against their foreign counterparts.

Nazifa Zaki, a former police official who is now a lawmaker from Kabul, said foreigners who "insulted" Islam should receive harsh punishment as a lesson to others.

The Koran incident was among a recent series of public missteps for the United States in Afghanistan, which also included the massacre of more than a dozen villagers allegedly by a U.S. soldier and photographs showing U.S. soldiers urinating on Afghan corpses.

U.S. President Barack Obama apologised to Karzai over the Koran burnings, which fuelled widespread demonstrations for more than a week.

Afzal Aman, head of the operations division at the Afghan Defense Ministry, said he did not expect such a decision to have an impact on Afghan and NATO soldiers' fight against the Taliban and its allies.

As the financial and human cost of the war mounts, NATO countries are planning to pull most of their soldiers from Afghanistan by the end of 2014.

Aman said lenient punishment might fuel militant propaganda, but he said Afghan troops would be ready. "We will wait to see what people say about it," he said. (Reporting by Rob Taylor, Missy Ryan and Mirwais Harooni in Kabul; David Alexander in Washington; Phil Stewart in Jeddah; Editing by Warren Strobel and Will Dunham)