U.S. Vice President Joe Biden said Monday the killing of two al-Qaida leaders in Iraq was " potentially devastating blows" to the terror network, and it demonstrated the Iraqi forces' capabilities.

Biden made the brief statement in the White House, after Iraqi Prime Minister Nuri al-Maliki announced earlier in the day that the two top leaders of al-Qaida in Iraq were killed Sunday in a joint operation of the Iraqi and U.S. forces.

Among the two killed was Abu Hamzah al-Muhajir, also known as Abu Ayyub al-Masri, military leader of al-Qaida in Iraq, while the other was Hamid Dawud Muhammad Khalil al-Zawi, also known as Abu Umar al-Baghdadi, who served al-Qaida in Iraq as the leader of the group's self-proclaimed Islamic State of Iraq.

"This action demonstrates the improved security, strength and capacity of Iraqi security forces. The Iraqis led this operation, and it was based on intelligence the Iraqi security forces themselves developed," Biden said.

The Pentagon said al-Masri replaced Abu Musab al-Zarqawi, who was killed in June 2006, and he was directly responsible for high-profile bombings and attacks in Iraq.

A paper displays photographs of a man the Iraqi government claims to be al-Qaida leader Abu Omar al-Baghdadi at a news conference in Baghdad, Iraq, Monday, April 19, 2010. [Xinhua]

Army Gen. Ray Odierno, commander of U.S. Forces Iraq, said the death of the duo was "potentially the most significant blow to al-Qaida in Iraq since the beginning of the insurgency."

The United States is slated to withdraw all its combat forces out of Iraq by the beginning of September. In an interview with Fox News Sunday, Odierno said the United States is on target to meet the deadline in accordance with an agreement with the Iraqi government.