In his new role as U.N. messenger of peace, George Clooney was playing himself.

The 46-year-old actor's arrival Thursday was greeted with "oohs" and "ahs" from dozens of people, mostly women, who crowded the lobby entrance for a glimpse and cell phone picture of him.

"Hi guys!" he said, stopping only briefly to pose for a picture with his parents and shake a few hands.

Clooney was touring the United Nations headquarters for a ceremony marking his designation for the special job by Secretary General Ban Ki-moon. He was just back from a trip to Sudan's Darfur region, arriving in the U.S. by way of India, a major contributor of U.N. peacekeeping troops.

Clooney and Jane Holl Lute, the assistant secretary general of peacekeeping operations, were part of "a technical assessment mission" visiting the joint African Union-United Nations peacekeeping operation in Darfur and the U.N. missions in the Central African Republic and Chad and in the Democratic Republic of Congo, U.N. officials said.

Clooney took on the job of promoting the world body's peacekeeping missions after waging his own campaigns for an end to the 4 1/2-year war in Darfur and for more humanitarian aid for the millions caught up in the conflict.

As the ninth U.N. peace envoy, Clooney was selected for his ability to focus public attention on critical international political and social issues.

He was accompanied Thursday by his parents, Nick and Nina Clooney, exchanging the glamour of Hollywood for a day spent among the diplomatic trappings of U.N. offices, a windowless press conference room, and several hours of back-to-back interviews with news media organizations.

The visit coincided with a meeting of countries Thursday that contribute troops to the 17 U.N. peacekeeping missions in countries from the Mideast and Africa to Haiti, Afghanistan and East Timor.

Clooney had been scheduled to attend that meeting but those plans were scrapped because several member countries did not want him there, according to U.N. officials.

The 17 missions involve more than 100,000 personnel, include 73,000 troops and more than 9,000 international police. One of the newest missions is the joint A.U.-U.N. operation in Darfur that started deploying this month.

Other messengers of peace are Michael Douglas, Elie Wiesel, Jane Goodall, Yo-Yo Ma, Daniel Barenboim, Paulo Coelho, Midori Goto and Princess Haya of Jordan.

Clooney also is a co-founder of Not on Our Watch, a humanitarian group that focuses global attention on Darfur's people and has raised more than $9.3 million for the region.