The explosion occurred outside the base near the town of Balad, about 50 miles north of Baghdad, the official, Saeed Kadhim, said.
He said the wounded had been taken to nearby hospitals.
U.S. officials in Baghdad could not confirm the attack.
By SADAQAT JAN, Associated Press Writer
ISLAMABAD, Pakistan - A top U.S. commander was in Pakistan on Monday on an unannounced visit to meet with senior officials during a crucial time in Pakistan's hunt for al-Qaida fugitives, an army spokesman told The Associated Press.
Gen. John Abizaid, the leader of U.S. Central Command, which overseas forces in the Middle East, Central Asia and the Horn of Africa, arrived in the past 24 hours, said Maj. Gen. Shaukat Sultan. Abizaid oversees the U.S. forces in Iraq and Afghanistan.
Sultan would not say who Abizaid met with, or whether the trip had anything to do with a week-old offensive by thousands of Pakistani forces against hundreds of al-Qaida holdouts in the tribal South Waziristan, a region bordering Afghanistan.
But he said Abizaid's visit was routine and had been planned before the current military action.
The Pakistani military believes a "high-value" target is holed up in the besieged area, but it is uncertain if it is al-Qaida commander Ayman al-Zawahri, Uzbek militant Tahir Yuldash, or another terrorist.
Pakistan insists no U.S. forces are involved in the offensive, though it acknowledges that about a dozen intelligence agents are helping with technical and logistical support.
The U.S. embassy could not immediately be reached for comment.
Abizaid's last known visit to Pakistan came on Jan. 16, when he met with President Gen. Pervez Musharraf on Friday. That trip was just a week after the last major operation by Pakistan's military in South Waziristan.
Ahmad Said al-Kadr, an Egyptian-born Canadian citizen who was suspected of being a top al-Qaida financier, was killed along with seven other suspects.