A dramatic attempt to impeach Tony Blair for misleading Parliament over the Iraq war could be launched in the wake of the long-awaited Chilcot report into the conflict.

MPs have begun to build support for an attempted prosecution of the former Labour Prime Minister after the 2.6million-word report is published on Wednesday.

A cross-party group is considering using an ancient Parliamentary mechanism to bring him to trial in Westminster.

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Tony Blair, seen here with wife Cherie on the day in 2007 when he left 10 Downing Street, is accused of duping the Commons over WMDs, which ultimately led to the loss of 179 British servicemen's lives

They say Mr Blair should be forced to answer claims he duped the Commons over the war, which cost the lives of 179 British troops.

The MPs believe they can argue that the ex-Labour leader should be impeached over allegations he breached his constitutional duties as Premier.

The power has not been used since 1806 when Lord Melville, a Tory minister, was charged with misappropriating official funds by the Commons. He was acquitted.

Mr Blair, who made claims about Saddam Hussein’s weapons of mass destruction that were contradicted by his own intelligence assessments, is expected to be heavily criticised in the Chilcot Inquiry report.

The long-awaited report by Sir John Chilcot, pictured, into the Iraq war will be published on Wednesday

One Westminster source said: ‘Impeachment is on our minds but we will need to digest the report. There is definitely a feeling that Blair must be properly held to account for his actions in the run-up to what was a disastrous war.’

One MP can trigger the process by proposing a motion. He or she would need to present evidence to support their case and this would form the basis of a document called the Article of Impeachment, drawn up by a committee of MPs.