BAGHDAD, IRAQ, DEC. 11 -- About 500 Americans appear to have decided to forgo evacuation and have chosen to remain in Iraq or Kuwait because they are either long-time residents or hold dual U.S. citizenship in either country, U.S. officials said today.

Many of those remaining behind are children of mixed-citizenship families.

An American evacuation flight from Kuwait left the tiny occupied country today with no Americans on board, essentially confirming that several hundred people who hold U.S. passports are expected to remain behind.

In Washington, the State Department announced another evacuation flight was expected to depart Kuwait on Thursday, after a final effort to locate any Americans who might wish to leave. The flight also is expected to take out the five remaining American diplomats at the beleaguered embassy in Kuwait City, effectively closing the facility.

Since the evacuation flights began last week, following Iraqi President Saddam Hussein's decision last Thursday to release all foreign detainees, more than 200 Americans have flown home, the State Department said today.

That number includes seven former U.S. hostages and one of their wives, who left tonight on a Boeing 747 bound for London. Another eight former hostages flew to Frankfurt on a Boeing 707.

About 85 of those who have left since Friday had been in Kuwait. Sixty-six of them were in hiding.

U.S. officials had thought that more Americans might be on today's flight, but no one signed up and no Americans showed up at the Kuwait airport. Instead, the plane flew only one Irishman and two Canadians to Baghdad. From there, they flew to Europe tonight.

{In Houston, Soviet Foreign Minister Eduard Shevardnadze called for creation in the Middle East of a zone that would be free of nuclear and chemical weapons and would include Iraq as well as Israel, Washington Post staff writer David Hoffman reported. Secretary of State James A. Baker III said he was sympathetic to the idea. Details, Page A29.}

As many as 510 Americans are still in Iraq and Kuwait, according to State Department deputy spokesman Richard Boucher. "As of today, we believe that as many as 310 Americans have chosen to stay in Kuwait. This includes 60 women, 215 children, and 35 males with dual Kuwaiti-American citizenship," Boucher said. "As many as 200 more Americans have chosen to stay in Iraq. Of these, 40 are women, 79 are children and 80 are men with dual Iraqi-American citizenship."

Many of those remaining are Americans married to Kuwaitis or Iraqis who have lived in either country so long they consider it home and do not intend to leave.

The 747 that flew to London carried a total of 313 persons, most of them British citizens who had been in hiding in Kuwait. About 160 Japanese, including 14 diplomats from the Japanese Embassy in Kuwait, left Baghdad today on a flight for Bangkok, Thailand.

As of today, only 10 diplomats remain in the U.S. Embassy in Baghdad and five in Kuwait. White House Press Secretary Marlin Fitzwater indicated that while the Kuwait facility will remain open on a "technical" basis, the U.S. flag will cease to fly over the embassy once the last diplomats leave. "As a practical matter, we won't have anyone there to tend the flag," he said.

Jeanette Pinot, the U.S. consul in Baghdad whose job it is to keep track of Americans in the two countries, said tonight that all the Americans who had been held as human shields at strategic sites in Iraq had been brought into Baghdad by today. All of them, except one American who had to return to the southern Iraqi city of Basra, have left on the evacuation flights.

Fourteen Americans left on flights from Baghdad today. Mike Nickman, of Grand Island, Nebraska, was the last one. "I'm very, very happy," he said. "I learned that if something looks like trouble, I'm going to get out while I have the chance. Why take a chance? It could have turned out worse."

The Bush administration said today that it has evacuated about 2,520 Americans and their family members from Kuwait since the Aug. 2 invasion by Iraq. An estimated 600 Americans were believed to have escaped from Kuwait and another 200 may have escaped from Iraq, the State Department said.

As for the number of Americans believed to be left in Kuwait, the U.S. charge d'affaires in Baghdad, Joseph Wilson, said tonight it "would be my guess" that there are "a few more." Earlier in the day, he said he expected the exodus from Kuwait to be over by "week's end."

"I think this is going to be a trickle" of departees from Kuwait from now on, said Pinot. "I think expecting people to come out in a week was a dream. . . . It's going to take awhile." Some people in hiding are "going to wait for a couple of weeks to see if it's safe," he added.

Several Westerners leaving Iraq said that they did not believe there were many more left in the country. "As far as I know, we're one of the last," said Tom Litrenta, 28 of Allentown, Pa., an irrigation project worker who took refuge at the U.S. Embassy in Baghdad. But a freed Irishman said some Westerners are remaining behind in Kuwait with the hope that the country will be liberated. "They're optimistic that somebody can do something soon," he said.

In Kuwait, "there was a communication breakdown between what was left of the embassy officials and the hostages," said the man who asked not to be identified out of concern for colleagues remaining there.

Iraq, which now considers Kuwait to be an annexed province, no longer honors Kuwaiti passports. Iraq considers citizens with dual passports to be Iraqis. Like other Iraqis, they are not free to leave the country.Washington Post staff writers Al Kamen and Dan Balz in Washington contributed to this report.