"I am very happy to announce that the two leaders have agreed that the cessation of hostilities and the end of the fighting will enter into force on 14 August, at 0500 hours GMT," Annan said in a statement.

The UN chief said he had been in touch with the two prime ministers to agree on a cease-fire date.

"As I promised the Security Council yesterday, I have today been in touch with the prime ministers of Israel and Lebanon to discuss with them the exact date and time when the cessation of hostilities called for by the Council will enter into force."

Annan said that he would prefer for the fighting to stop immediately based on a cease-fire resolution adopted unanimously by the UN Security Council late Friday.

"Preferably, the fighting should stop now to respect the spirit and intent of the Council decision, the object of which was to save civilian lives, to spare the pain and suffering that the civilians on both sides are living through," he said.

The U.N. secretary-general also called on both sides to halt the fighting immediately, and assured them that the U.N. forces on the ground would work with them to monitor compliance of the Security Council resolution approved Friday to stop the hostilities.

"So I urged the parties to stop immediately and I would want to assure them the United Nations forces on the ground, UNFIL, will work with them to implement the agreement and will monitor compliance," he said.

The U.N. Security Council on Friday unanimously adopted a resolution calling for an end to the bloodshed between Israel and Hezbollah and for the deployment of a 15,000-strong international peacekeeping force to prevent further conflict.

Resolution 1701, drawn up by the United States and France after protracted haggling, also calls for Israeli troops to be withdrawn from southern Lebanon after an end to the fighting. Until then the world body had been criticized for failing to take any action to help end the bloodshed.

The council called for "a full cessation of hostilities based upon, in particular, the immediate cessation by Hezbollah of all attacks and the immediate cessation by Israel of all offensive military operations."

More than four weeks of conflict have left more than 1,100 dead, mainly in Lebanon.

While Israel pursued its military offensive on Friday, Israeli Prime Minister Ehud Olmert decided to urge his cabinet to accept the resolution when it meets Sunday, a government spokesman said.

Lebanese Prime Minister Fouad Siniora said his government unanimously approved the resolution on Saturday, and Hizbollah leader Sayyed Hassan Nasrallah said his fighters would abide by it once Israeli forces also adhere to it.

The text calls on Lebanon and the U.N. Interim Force in Lebanon (UNIFIL) to "deploy their forces together" in southern Lebanon, while Israel must "withdraw all of its forces from southern Lebanon in parallel" to the deployment.