(Adds Correa, Chavez, Sarkozy comments)

By Brian Ellsworth

CARACAS, March 5 (Reuters) - Venezuela deployed tanks and air and sea forces toward the Colombian border on Wednesday in its first major military mobilization in a crisis that has raised fears for regional stability.

Venezuela's military said it started sending 10 tank battalions toward the border and activated its air force and navy. Military analysts estimate such a mobilization could include more than 200 tanks.

The action escalated tensions over Colombia's weekend raid to kill rebels inside another South American neighbor, Ecuador, which Venezuelan President Hugo Chavez, an ally of leftist Ecuadorean President Rafael Correa, said could spark war.

While Ecuador and Venezuela have moved soldiers toward their borders with Colombia, Wednesday's movements were the first signs of heavy firepower being mobilized.

Colombia lambasted its neighbors for harboring FARC guerrillas, but said it would not deploy extra forces.

Governments worldwide urged the nations to defuse tensions as Venezuela and the United States blamed each other for the intensifying crisis.

"Our movement is totally defensive, fortifying our border posts due to the threat. ... They are war, we are peace," Chavez said at a news conference in Caracas with Ecuador's Correa, who is touring the region to lobby against Colombia.

The crisis pits OPEC nations Venezuela and Ecuador against Colombia, which receives billions of dollars in U.S. military aid and has received public backing from President George W. Bush in the crisis.

On Wednesday, the United States questioned why Venezuela is involved in a dispute Colombia and Ecuador should work out on their own, White House spokeswoman Dana Perino said.

"We do think it's curious that a country such as Venezuela would be raising a specter of military action against a country who was defending itself against terrorism. That says a lot about Venezuela," Perino said.

Chavez says Bush is using conservative Colombian President Alvaro Uribe as a proxy in a plot to invade Venezuela, a major oil exporter to the United States. Washington denies the charge, similar to many that the Cuba ally has made before.

TROOPS ON THE MOVE

In the second day of an emergency session in Washington, the Organization of American States stopped short of condemning Colombia, as Correa had demanded.

But the OAS agreed in a resolution that Colombia violated international law when it killed more than 20 Marxist FARC guerrillas, including a top leader of the insurgency group, inside Ecuador.

"Thank you OAS, it's a step forward, we are content. But we will never be satisfied until they sanction those who wanted to violate the sovereignty of our fatherland," Correa said.

French President Nicolas Sarkozy, who has backed Chavez's mediation this year to free hostages held by Colombian rebels, urged the Venezuelan leader in a phone call to show restraint.

Sarkozy also warned the FARC's leader he would be viewed as a murderer throughout the world if he let die hostage Ingrid Betancourt, a French-Colombian national seized by rebels six years ago. Betancourt is reported to be in very bad health.

In Venezuela, a Reuters witness saw three armored vehicles on carrier trucks and four troop-movement vehicles driving in the direction of the border near the rural town of El Mojan. Local TV also showed fighter jets flying, albeit far from the border, and buses ferrying troops in the direction of the frontier.

Colombia's borders with Venezuela and Ecuador stretch in an arc from the Caribbean Sea to the Pacific Ocean on the western shoulder of South America. The borders remain open, but Ecuador and Venezuela have cut diplomatic ties.

Despite the brinkmanship and risk of military missteps, political analysts said a military conflict was highly unlikely, especially as governments focused on diplomacy.

(Additional reporting by Pat Markey in Bogota, Manuel Hernandez in El Mojan and Adriana Garcia and Kristin Roberts in Washington; Writing by Fiona Ortiz, editing by Saul Hudson and Cynthia Osterman)

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