UK-US relations in the run-up to the Iraq war are to come under scrutiny as ex-US Ambassador Sir Christopher Meyer gives evidence to the war inquiry.

His evidence is expected to touch on the personal relationship between Tony Blair and former President Bush and the extent to which this influenced policy.

The inquiry was told on Wednesday of reports days before the war that Iraq had dismantled its chemical weapons.

But Foreign Office officials insisted the war was still justified.

The inquiry is looking into UK involvement in Iraq between 2001 and 2009, with the first few weeks focusing on policy in the build-up to the 2003 US-led invasion.

Sir Christopher, UK Ambassador to Washington between 1997 and 2003, will take centre stage on the third day of public hearings.

Critics of the war claim that the US had already decided to topple Saddam Hussein in 2002 and that the UK had agreed to go along with this – claims both countries have denied.

The reasons for going to war in Iraq – including the now discredited claim that Saddam Hussein had weapons of mass destruction which could be used within 45 minutes of an order being given – remain a long-standing source of controversy.