(Adds team returned safely, background, quotes, paragraphs 3-7)
WASHINGTON, Aug 13 (Reuters) - A team including personnel from the U.S. military and the U.S. Agency for International Development landed on Iraq's Mount Sinjar early on Wednesday to assess how to evacuate civilians, a U.S. official said.
The official said the team flew in darkness early in the morning to the mountain, where thousands of people, including members of the Yazidi religious minority, have fled to escape an advance by Sunni fighters from the Islamic State militant group.
"They were there last night and they did an assessment," said the official, saying this occurred early on Wednesday in Iraq.
A second U.S. official said fewer than 20 personnel were involved in the assessment of the situation and all had returned safely to the Kurdistan capital of Arbil by military air.
The United States has not ruled out using ground forces in an operation to extract thousands of desperate civilians trapped on the mountain by Islamist militants, but they will not engage in combat, a senior White House official said earlier.
A team of 130 U.S. military personnel is in Arbil urgently drawing up options ranging from creating a safe corridor to an airlift to rescue those besieged on Mount Sinjar for over a week.
The U.S. Agency for International Development has also deployed a so-called Disaster Assistance Response Team (DART) team to Iraq to assess the humanitarian situation. (Reporting By Arshad Mohammed and David Alexander; Editing by Sandra Maler)