The Pentagon hawk responsible for much of the planning of the war against Iraq has resigned.

Douglas Feith is the second leading hardliner in America´s campaign against international terrorism to step down this year.

His resignation follows the departure of John Bolton from the state department. But the administration´s most prominent hardliners, Donald Rumsfeld, the defence secretary, and the new secretary of state, Condoleezza Rice, remain in place.

Mr Feith ignored pleas from Mr Rumsfeld, his boss and close ally, for him to stay.

A Pentagon spokesman said Mr Feith had tired of the "up before the kids and go to work, home after they go to bed routine".

The New Yorker magazine last week accused him of working with Israeli officials to select possible targets for a pre-emptive strike against Iran´s nuclear programme. The Pentagon strongly denied the report.

His 1,500-strong planning staff, which forms Pentagon policy for the war on terrorism, is reported to be facing three separate investigations, one by the FBI and two by congressional committees.

One is looking into claims that classified papers on Iran were leaked from his staff to Israeli lobbyists and officials.

A congressional committee is also reported to be investigating whether officials from his staff planned to destabilise the Syrian regime without presidential approval.

A long-standing friend of Israel and hardline opponent of Saddam Hussein´s Iraq, Mr Feith sometimes explained the administration´s thinking more clearly than its official spokesmen.

A month before the invasion of Iraq in 2003 he offered what may have been its true motivation for war in Iraq: the need to pre-empt action by rogue states.

Mr Feith, 51, a Washington lawyer, is a protégé of Richard Perle, a senior Pentagon appointee during the Reagan era who won the nickname "the Prince of Darkness" for his hawkish views during the Cold War. (© Copyright of Telegraph Group Limited 2004. 01/28/05)