Iraq war? What Iraq war?

The looming tenth anniversary of the Iraq war is set to prompt the next big divide between the Conservatives and Liberal Democrats.

Nick Clegg is expected to defy a letter from William Hague to Cabinet members asking them to avoid talking about the rights and wrongs of Britain's participation in the US-led March 2003 invasion of Iraq.

The foreign secretary wants to gag members of the government on the grounds that Sir John Chilcot's inquiry into Tony Blair's most controversial decision has not yet completed its work.

"The idea that Nick Clegg and the Liberal Democrats will be mute on the tenth anniversary of the war in Iraq will get very short shrift indeed," a senior Lib Dem source told the Guardian.

"The party called it right on the Iraq war a decade ago. The Lib Dems won't shirk from our views on this illegal and unjust conflict a decade on."

Clegg is expected to make a speech ahead of the anniversary underlining the difference between his party's vigorous anti-war stance and that of the Conservative party, which voted with Blair in favour of military action.

According to the newspaper the letter from Hague urged ministers to avoid "prejudging Chilcot", but gave them a green light for "acknowledging the sacrifices of the armed forces". In total 179 British armed services personnel lost their lives during the invasion and its prolonged, bloody aftermath.

Chilcot's inquiry has now been underway for over three years and is not expected to report until the end of 2013 at the very earliest.

It is set to exceed over one million words in length and has been hampered by the serious illness of Martin Gilbert, a member of the inquiry panel.

Letters will be sent to those set to be criticised by the report, giving them the opportunity to make rebuttals, no earlier than this summer, Chilcot told Downing Street last summer.