The former head of the Army has accused Tony Blair and Gordon Brown of letting down British troops in Iraq and Afghanistan.

General Sir Richard Dannatt branded Mr Brown "malign" for failing to fund the armed forces adequately and said Mr Blair lacked the "moral courage" to make his then Chancellor deliver the money that was needed.

The accusations come in a book, entitled Leading From the Front, serialised in the Sunday Telegraph today.

General Dannatt was unusually outspoken about the equipment and manpower needs of the Army during his time as Chief of General Staff from 2006-09, and some commentators believe he was passed over for the post of head of the armed forces as a result.

Shortly after his retirement from the military last year, it was announced that he would become a defence adviser to Conservative leader David Cameron, but he decided not to take up a post with the Prime Minister after he took office in May.

In his book, General Dannatt says that evidence for Iraq's possession of weapons of mass destruction - the official justification for Britain's involvement in the 2003 invasion - was "most uncompelling" and the planning for the aftermath of war an "abject failure".

"History will pass judgment on these foreign adventures in due course, but in my view Gordon Brown's malign intervention, when Chancellor, on the SDR by refusing to fund what his own government had agreed, fatally flawed the entire process from the outset," he wrote.

"The seeds were sown for some of the impossible operational pressures to come."

Mr Blair "lacked the moral courage to impose his will on his own chancellor", said the general.