WASHINGTON (AFP) - President Barack Obama said he had approved strict rules for when the United States can carry out drone strikes against terror suspects abroad, saying lethal force could be used when no other alternatives exist.

Mr Obama for the first time laid out the criteria for using "lethal force" outside of warzones, while defending the need to continue the CIA strikes when necessary.

Here are the main points of the policy guidelines released by the White House on Thursday regulating the drone bombing raids, which until now have been carried out secretly by the Central Intelligence Agency in Pakistan, Yemen and Somalia.

- Lethal force will not be used as punishment but "only to prevent or stop attacks against US persons, and even then, only when capture is not feasible and no other reasonable alternatives exist to address the threat effectively."

- Resorting to force must have a legal basis and "only against a target that poses a continuing, imminent threat to US persons. "It is simply not the case that all terrorists pose a continuing, imminent threat to US persons; if a terrorist does not pose such a threat, the United States will not use lethal force," the White House said.

- Before ordering lethal strikes, there must be: "near certainty" that the target is present, that civilian non-combatants will not be injured or killed, an assessment that capture is not feasible, an assessment the local government "cannot or will not effectively address the threat" and an assessment that no other "reasonable alternatives exist" to address the threat.

- The United States will respect "sovereignty and international law." The laws of war and international legal principles will "impose important constraints on the ability of the United States to act unilaterally - and on the way in which the United States can use force."

- If a terror suspect being targeted is identified as a US national, "the Department of Justice will conduct an additional legal analysis to ensure that such action may be conducted against the individual consistent with the Constitution and laws of the United States."

- But the new procedures for lethal strikes "do not limit the president's authority to take action in extraordinary circumstances when doing so is both lawful and necessary to protect the United States or its allies."

- In his speech, Mr Obama addressed questions about the potential use of armed drones on US territory: "For the record, I do not believe it would be constitutional for the government to target and kill any US citizen - with a drone, or a shotgun - without due process. Nor should any president deploy armed drones over US soil."

Mr - Obama said he was open to proposals from lawmakers for more "oversight" of the drone strikes, either by a special court or an independent body within the executive branch.

However, he said that each "option has virtues in theory, but poses difficulties in practice."