WASHINGTON (AP) _ The American military has ''no role to play'' in Liberia's internal conflict even though more than 2,000 marines are poised to help evacuate U.S. citizens from the African nation, officials said Tuesday.

Despite embattled President Samuel Doe's plea that the United States ''come to the aid'' of the Liberian people, officials in Washington have so far rejected the idea of involving U.S. servicemen in the West African nation's civil strife.

''The U.S. government ... is taking appropriate steps to assist American citizens to leave Liberia in the event that they are in more immediate danger and no longer able to leave the country by other means,'' State Department spokesman Richard Boucher said.

The Navy's four-ship flotilla in international waters off the Liberian coast ''solely on a contingency basis to evacuate American citizens if it becomes necessary,'' Boucher said.

''The U.S. military has no role to play in this conflict,'' he stressed in a statement read to reporters.

White House spokesman Marlin Fitzwater reported that 33 Americans were evacuated from Liberia on Monday and thousands more had previously left.

He said 70 U.S. officials and an estimated 1,200 private citizens were left in the country.

''Our primary concern is protecting U.S. citizens,'' Fitzwater said.

In addition, though, the United States agreed to evacuate Soviet diplomats from Liberia if that becomes necessary, Defense Secretary Dick Cheney said in an interview Tuesday with Hearst Newspapers.

''It hasn't been required yet, but the fact of the matter is they (the Soviets) have asked for - and we have agreed - to provide assistance to their people in Liberia,'' Cheney said in the interview.

Between 10 and 15 Soviet diplomats remained in Liberia, the Hearst report said.

President Bush dispatched the warships from the Mediterranean-based 6th Fleet over the weekend in case the struggle between forces loyal to Doe and those supporting rebel leader Charles Taylor block the exit of any Americans who wish to leave.

Boucher said the rebels continued to advance towards the capital of Monrovia and that flights had been suspended from Roberts International Airport, where there were ''reports of fighting.''

The spokesman said commercial aircraft were continuing to use Spriggs Payne Airfield, about five miles from the center of the capital city, and that the road to Sierra Leone ''remains usable.''

Pentagon spokesman Pete Williams stressed the precautionary nature of the deployment of the Marine group. He said he couldn't define any ''trigger'' that might bring them ashore to assist in an evacuation, including the event that all air travel would be stopped.

He said he had no indication that there were Americans who wanted to leave but couldn't.

Williams declined to outline any plan for a possible evacuation, citing security concerns.

However, he did say the Marines could be used for such things as ''providing security at the airport, or assisting Americans in leaving from some other point - out to the ships, or to another country.''

Williams said that formally, the State Department must first request assistance from the Pentagon for using the Marines, and then the president must authorize their use.

''What would cause that (to happen)? It has to be an assessment that the Americans are in danger and that the evacuation would be the right thing to do, but I can't give you a list of all the things that would have to happen,'' he said.

Williams, asked about the possible use of the Marines to assist the Doe government, echoed Boucher's statement that the United States has no role in Liberia's internal conflicts.

He said the Doe government was well aware of the reasons behind the deployment of the Marine readiness group, calling it ''a reasonable precaution to take.''

Williams said there had been requests for U.S. assistance in the possible evacuation of officials from other nations, but he declined to specify which nations had made the requests.