The United States Friday called for an immediate ceasefire in the conflict in Georgia's South Ossetia region and a withdrawal of Russian combat forces from the area. Secretary of State Condoleezza Rice, who made the appeal, is sending a senior diplomat to try to help mediate the crisis. VOA's David Gollust reports from the State Department.

Rice and other top U.S. officials are conducting urgent telephone diplomacy aimed at ending the hostilities in South Ossetia, which are described as the worst fighting since the separatist war in the region in the early 1990's.

Russia sent combat troops into the breakaway region this week and staged air strikes after Georgian government forces moved to assert control over South Ossetia, which has resisted central authority since the former Soviet republic's independence in 1991.

In a written statement urging an immediate ceasefire, Rice called on Russia to cease aircraft and missile attacks on Georgia, to respect the neighboring country's territorial integrity, and to withdraw its ground combat forces from Georgian soil.

The Secretary of State said the United States is working actively with European partners to launch an international mediation effort, and said they are urgently seeking Russia's support for these efforts.

Rice's statement followed an announcement by State Department Acting Spokesman Gonzalo Gallegos that a senior U.S. diplomat will join European colleagues in a joint mediation effort.

"We urge all parties, including Georgians, South Ossetians and Russians to de-escalate, and avoid conflict. We're working on mediation efforts to secure a cease-fire. We are sending an envoy to the region to engage with the parties in the conflict. Secretary Rice and other senior officials have spoken with, and continue to work with, the parties to seek an end to hostilities," he said.

Officials later said the U.S. envoy will be Deputy Assistant Secretary for European and Eurasian Affairs Matthew Bryza, the State Department's top expert for the Caucasus region.

He is expected to leave Washington sometime during the weekend after details of the mediation effort are coordinated with European governments.

The Bush administration has developed close ties with the government of American-educated Georgian President Mikhail Sakashvili, and has strongly supported its ambitions for NATO membership.

NATO promised eventual membership for Georgia and Ukraine at its summit in Bucharest earlier this year, a move that prompted the then Russian President Vladimir Putin to pledge more support for South Ossetia and the other breakaway Georgian region, Abkhazia.

Russia has maintained a peacekeeping presence in the two areas since the 1990's conflict, and is accused by the Tbilisi government of actively supporting local separatists.

Officials here gave no specifics of Secretary Rice's diplomatic outreach effort. But Russian Foreign Minister Sergei Lavrov said in Moscow he had three telephone conversations with Rice.

Lavrov's office said he urged the United States to press Georgia to halt what he described as aggression against South Ossetia and return to compliance with earlier agreements.