The Liberal Democrats leader Nick Clegg said on Sunday Iraq was the biggest strategic failure of British foreign policy for decades, demanding for an "early and full" withdrawal of British troops.
Both opposition leaders made the statements in a BBC program.
Hague said "clarity" was needed on the future for Britain's deployment in Iraq.
"It is very important to commence the full-scale Privy Council inquiry into the origins and conduct of the war ... Lessons have got to be learned, and visibly learned, and we have got to start on that process now. We will be raising this again in Parliament in the coming weeks," Hague said.
Clegg said "It is now time to recast British foreign policy in Britain's interests, not those of Washington, starting with an early and full withdrawal of all remaining British troops in Iraq."
Groups opposed to the continuing war in Iraq are marking the fifth anniversary of the Iraq invasion with demonstrations. Thousands of protesters marched in London and Glasgow on Saturday ahead of the March 20 anniversary to demand Britain withdraw its troops from both Iraq and Afghanistan.
There have been four inquiries into different aspects of the Iraq war. But there has not been an inquiry made focusing on how the government's decision to join the US-led invasion.
The government has indicated it will sanction a high-level inquiry into the war once British troops had been withdrawn.
(Xinhua News Agency March 17, 2008)
