Gunmen from the so-called Islamic State of Iraq and Levant (ISIL) seized Iraq's second-largest city as troops threw away their uniforms and abandoned their posts.
Maliki asked the Parliament to declare state of emergency in whole the country, while calling on all neighboring countries to closely watch their borders with Iraq.
Militants have launched major operations in Nineveh, Anbar, Diyala, Salaheddin and Baghdad provinces since Thursday, killing scores of people and highlighting both their long reach and the weakness of Iraq's security forces.
In early January, the government lost control of Fallujah, just a short drive from Baghdad.
More than 900 people were killed last month, according to figures separately compiled by the United Nations and the government.
So far this year, more than 4,600 people have been killed, according to AFP figures.
SHI/SHI