CAIRO (Reuters) - Iraq's parliament voted on Monday (Nov 2) to bar the government from passing key reforms without its approval in an effort to restrict Prime Minister Haider al-Abadi, parliamentarians said.

The chamber took the step after Abadi unilaterally passed reforms in August it considered a violation of the constitution such as sacking the vice presidents and deputy prime ministers and cutting the salaries of government employees.

"What we have warned against in our letter to Abadi last week of taking unilateral reforms now came to an end. Under this resolution no more absolute authorities for the prime minister,"an MP, who asked to remain anonymous, told Reuters.

Last week more than 60 members of Iraq's ruling State of Law coalition threatened to withdraw parliamentary support for Abadi's reforms if he does not respond to their demands for wider consultation.

Growing political tensions could undermine efforts to tackle an economic crisis and form a united front against Islamic State in Iraq and Syria (ISIS) militants, who pose the biggest security threat to Iraq since a US-led invasion that toppled Saddam Hussein in 2003.

Abadi announced a reform campaign in August after protests erupted over graft and poor water and electricity services in Iraq, a leading OPEC oil producer.

The steps are intended to scrap senior political offices that have become a vehicle for patronage for some of the most powerful people in Iraq and combat incompetence which has undermined the battle against militancy.

Some of the measures have been implemented, while others appear to have stalled. Iraq's three vice presidents, whose positions were to be cut, remain in place.