"Regarding federalism, we think that it is necessary to form one entire region in the south," said Abdul Aziz al-Hakim, leader of one of the Shia Muslim parties in the Iraqi government.
Al-Hakim, head of the Supreme Council for the Islamic Revolution in Iraq (SCIRI), openly called for an autonomous Arab Shia region in central and southern Iraq where the Shia presence is strongest.
He was speaking in the Shia city of Najaf, 130km south of Baghdad.
It is the first time that al-Hakim, who headed the Shia list of parliamentarians that won a sweeping majority in the 30 January legislative elections, has stated the need for an autonomous region so clearly.
Federalism was also favoured by another Shia leader.
"Federalism has to be in all of Iraq. They are trying to prevent the Shia from enjoying their own federalism," Hadi al-Amiri, head of the Badr Brigades militia, told thousands of Shia gathered in the southern city of Najaf.
"We have to persist in forming one region in the south or else we will regret it. What have we got from the central government except death?" al-Amiri said.
The calls for a Shia state come at a critical time when Iraqi leaders are trying to finish a draft constitution to submit to parliament before a self-imposed 15 August deadline.
At least three people are reported killed across Iraq on Thursday, including a top intelligence officer at the Defence Ministry.
"Federalism has to be in all of Iraq. They are trying to prevent the Shia from enjoying their own federalism"
head of the Badr Brigades
A police lieutenant was shot dead in the Yarmuk district of Baghdad, an official with the Interior Ministry said.
A Christian engineer, Said Adib Touma, 32, was kidnapped in the early morning from the northern town of Kirkuk and his body was found two hours later, a police officer said.
In another attack, intelligence officer Lieutenant-Colonel Ibrahim Khalil was shot dead in the Junaina neighbourhood in northern Basra, an official with the Defence Ministry said without giving further details.
Southern Iraq and especially Basra, which is under the control of British forces, is a relatively calm region compared to the rest of Iraq.
But on Tuesday, nearly 1000 people demonstrated in Samawa, the provincial capital of Muthanna, demanding jobs and services.
Al-Sadr's followers will stage a
silent protest on Friday
The demonstration was part of such protests that are cropping up across Iraq as the war-torn country suffers shortage of electricity and clean drinking water.
Followers of Shia leader Muqtada al-Sadr will hold a silent protest in Baghdad on Friday against the rampant violence and lack of basic amenities in the war-torn country.
"It will be a silent protest with no banners, posters and slogans," a statement from al-Sadr office said on Thursday.