British officials secretly discussed the prospects for regime change in Iraq in late 2001 - more than a year before the invasion - the official inquiry into the war has been told.

The revelation came on the first day of public hearings in London to the inquiry, headed by Sir John Chilcot.

It was told that Foreign and Commonwealth Office (FCO) officials drew up an internal "options" paper which included the possibility of ousting Saddam Hussein - but the suggestion was rejected.

Sir William Patey, the then head of the FCO's Middle East department, said the idea had been swiftly rejected on the grounds that there was "no basis in law" for such action.

The decision to go to war in Iraq sparked one of the biggest public protests of recent times Full Image

The inquiry, which took evidence from a series of senior FCO and Ministry of Defence officials, heard that a two-page paper was drawn up against a background of growing impatience in the United States with the strategy of "containment" of Saddam. The international sanctions regime was "in trouble", while there were increasing concerns that Saddam was making progress in his efforts to acquire weapons of mass destruction (WMD).

"This is a paper I commissioned from my staff and said 'Come on, let's have the whole range of options out here. Nothing's off the table'," said Sir William. "The options went from "'hard' containment to 'soft' containment, to the lifting of sanctions, to - I have to say - we had at the end the regime-change option, which was dismissed at the time as having no basis in law."

He added: "It was very much an internal paper. We didn't go into how to achieve regime change."

However the inquiry heard that even in early 2001, elements of the new US administration of President George Bush were already discussing the possibility of "regime change" in Iraq.

Sir Peter Ricketts, who was chairman of the Joint Intelligence Committee (JIC), said Britain wanted a strengthened "smart sanctions regime" - a position initially backed by senior figures in the Bush administration like Secretary of State Colin Powell. They were aware, however, of other influential figures in Washington who were already taking a harder line.

"We were conscious that there were other voices in Washington, some of whom were talking about regime change," he said.