Some MPs objected angrily to a map drawn up by Kurds in northern Iraq, which showed the disputed city of Kirkuk as part of the Kurdish area.

The draft law is being presented by Shia groups, some of whose leaders want an autonomous region in southern Iraq.

Some Sunni Arabs fear a break-up of Iraq, leaving their community without access to oil reserves.

They want constitutional amendments to limit the potential for regions to break away.

'Marginalised'

Kurdish and Shia MPs tabled bills which would allow Iraqi provinces to merge and form federal regions.

Although the more radical Kurdish bill was rejected, the Shia-proposed draft law was given a first reading, the French news agency AFP reported.

If passed, the law would allow Iraq's 18 provinces to hold referendums to decide on whether to merge with neighbouring areas, enabling them to form larger regions with broad powers of self-rule.

The BBC's David Loyn in Baghdad says MPs only have until 22 October to resolve the issue, which is threatening to derail other business.

Iraqi lawmakers were also due on Tuesday to name the members of a committee to draft changes to the constitution.