Maliki, who is under pressure from Washington to speed up the rebuilding of local forces, said Iraq's military and political leaders needed to step up their efforts to do so.
"Allow me to say that we are late, very late, to reconstruct, to rebuild our forces for reasons that I do not want to mention here," he said as he took over the security of the Shiite province of Karbala from the American military.
Karbala became the eighth of Iraq's 18 provinces to be handed over to local forces by the US-led coalition.
The delay in rebuilding Iraqi forces has hampered Washington's plans to withdraw its forces from the war-ravaged country.
"We demand that the military and police leadership make more efforts to reconstruct and rebuild the security forces in order to take over control of the rest of the provinces," Maliki said.
"These provinces are waiting to be secured by their own sons once again."
Washington and Baghdad had hoped that Iraqi forces would take control of most of the provinces this year and had even declared 2007 the "Year of Security" in Iraq.
But a US congressional report in September said Iraq was 12-18 months away from assuming complete security control, largely because of a corrupt police force.
The report by Marine General James Jones, the former top US commander in Europe, said Iraqi forces were improving "but not at a rate sufficient to meet their essential security responsibilities."
Maliki's concern was highlighted further on Monday when a suicide bomber riding a bicycle blew himself up at police headquarters in Baquba, the restive city northeast of Baghdad.
Brigadier General Kudair al-Timimi of Baquba police said the early morning blast killed 27 policemen and wounded another 21 people, including 18 policemen.
Baquba, the capital of Diyala province, is one of the most dangerous regions in Iraq where US and Iraqi forces are waging a continuing campaign targeting insurgents, especially Al-Qaeda in Iraq fighters.
Insurgents have stepped up attacks in Diyala in recent days and Monday's bombing comes a day after 11 Sunni tribal leaders from the province were kidnapped in Baghdad.
They were seized in Baghdad's northern neighbourhood of Al-Shaab which has a strong Shiite militia presence, a security official said, adding that the tribal leaders were part of a local movement opposing Al-Qaeda in Iraq.
In recent months the US military has been supported by Sunni tribal leaders as well as nationalist former insurgents in its fight against Al-Qaeda in Diyala province.
Monday's bombing took the overall Iraqi death toll this month to more than 330, but this is still one of the lowest since February 2006.
An attack on the Al-Askari shrine in the central city of Samarra that month sparked a wave of brutal sectarian bloodletting that has killed tens of thousands.
The violence peaked in January this year, when the interior, defence and health ministries reported 1,992 deaths.
US and Iraqi commanders have hailed the declining casualty toll as proof of the success of a joint crackdown on sectarian militias launched in and around Baghdad in February this year.
On Wednesday Lieutenant General Ray Odierno, the US second-in-command in Iraq, said there was a "downward trend" in attacks since June.
Meanwhile, the handover of Karbala took place amid tight security in a sports stadium.
The province, some 80 kilometres (50 miles) south of Baghdad, is relatively peaceful compared to some other central and western regions of Iraq, but is emerging as a flashpoint of Shiite rivalry.
Karbala, home to the shrines of two of Shiite Islam's most revered imams -- Imam Hussein and Imam Abbas -- was the site of a bloody firefight in August during a major religious festival in which at least 52 people were killed.
The other Iraqi provinces handed over by US-led forces to date are Maysan, Muthanna, Dhi Qar and Najaf in the central and southern regions and the three northern Kurdish provinces of Arbil, Dohuk and Sulaimaniyah.
Maliki on Monday said Iraqi forces would take control of the southern province of Basra, currently under the control of around 5,200 British troops, in mid-December.
