Ham, the U.S. military commander in Mosul, said the cause of the explosion is under investigation.
"The killed include U.S. military personnel, U.S. contractors, foreign national contractors, and Iraqi Army. The wounded also come from those various groups," he said.
Earlier today, a Pentagon official who asked not to be identified said the explosion was caused by an attack on the forward military operating base. The official said there were "an unknown number of rounds in a rocket and mortar attack."
The Al-Qaeda-linked Army of Ansar Al-Sunnah group has claimed responsibility for the attack, in a statement attributed to it on an Islamist website. Its authenticity could not be immediately confirmed.
Meanwhile, British Prime Minister Tony Blair flew into Baghdad today in a surprise visit designed to boost prospects for Iraqi elections in January.
At a news conference in Baghdad's protected Green Zone with interim Prime Minister Iyad Allawi, Blair said there is no question of running away from the insurgents.
"The danger that people feel here is coming from terrorists and insurgents who are trying to destroy the possibility of this country becoming a democracy. Now, where do we stand in that fight? We stand on the side of the democrats, against the terrorists," Blair said.
Blair, on his first visit to Baghdad, said those behind the violence are a minority. And he praised the courage of the Iraqi officials working for the government at a difficult time.
"When I meet the people working alongside the United Nations, Iraqis in fear of their life every day because they are trying to bring freedom and democracy to their people -- when I see their courage and their determination and know that they speak for the vast majority of people in Iraq who want that democracy and freedom, then I know that we are doing the right thing," Blair said.
Blair and Allawi both said the elections scheduled for 30 January will go ahead despite an upsurge in bloodshed. On 19 December, three Iraqi Election Commission officials were killed while twin suicide car bombings killed 66 people yesterday.
Allawi said the polls should be open to all Iraqis. "We look forward for this election to be inclusive," he said. "All Iraqis should participate in this election, and whoever is not going to have the chance, the doors will be open for everyone to be included in the political process as we move steadily in establishing the rule of law, human rights, and the constitution for Iraq."
Blair also met with top U.S. officials. And he was widely expected to visit British troops in the southern city of Al-Basrah before leaving for Israel to promote new peace initiatives.
In other developments, a member of the governing council in Diyala Province, Talib Ibrahim, was shot dead in the northern city of Ba'qubah.
In Baghdad, interim Interior Minister Falah al-Naqib said 1,000 policemen have been killed since the U.S.-led coalition reestablished Iraq's security forces.
(compiled from agency reports)[For the latest news on Iraq, see RFE/RL's webpage on "The New Iraq".]