The British military said an army officer has been arrested in Afghanistan on suspicion of leaking official secrets.
The Ministry of Defense said the officer was being flown back to Britain for questioning. It said his case has been handed over to London's Metropolitan Police.
If charged and convicted, the officer could face a maximum 14-year jail sentence.
The Sun newspaper on Wednesday identified the officer as Lt. Col. Owen McNally. The newspaper said he had leaked figures about civilian deaths in coalition operations to a worker from a human rights group.
Last year, Human Rights Watch said civilian deaths in Afghanistan from US and NATO air strikes nearly tripled between 2006 and 2007, from 116 to 321.