The Archbishop of Canterbury, Dr Rowan Williams, has said that US President George W Bush and British Prime Minister Tony Blair might have come to a different conclusion on whether to invade Iraq if they had taken the time to pray together.

In an interview with the BBC's Newsnight late on Wednesday evening, Dr Williams was questioned on whether Blair had been right in not praying with Bush in the run-up to the invasion of Iraq.

He answered: "I am sure he should have prayed and I think perhaps he should have prayed with George Bush."

Dr Williams added that had the leaders prayed together, they might not necessarily have received the answer they wanted.

"Praying doesn't mean you get the answer you want. It doesn't mean you get the answer the other person wants either."

Blair is an Anglican who often attends mass with his Catholic wife Cherie Blair while Bush is a born-again Christian who credits his return to Christ to the influence of renowned US evangelist Billy Graham. In the aftermath of the Virginia Tech tragedy Bush called on the US to pray for the victims and their families and encouraged them to remember them further in the US's National Day of Prayer on 3 May.

During his Newsnight interview, Dr Williams challenged the now famous remark from Downing Street media chief Alastair Campbell, "we don't do God".

Archbishop Williams said: "I think prime ministers as individuals ought to 'do God', because I think everybody ought to.

"I don't expect Government to be talking religion. I do expect Government to be giving space and opportunity for the kind of moral discussion informed by religion, as by many other strands of humanistic thought."

His comments follow a lecture earlier in the week in which Dr Williams challenged politicians to rediscover the moral energy and vision that had inspired William Wilberforce to campaign for the abolition of the slave trade.

In his lecture in Hull, the birthplace of Wilberforce, Dr Williams said that politics had to become more than simply a management system.

"The more politics looks like a form of management rather than an engine of positive and morally desirable change, the more energy it will lose," he said.

Archbishop Williams told Newsnight that he did not think Blair's Christianity was off-putting to the British public except in the context of the Iraq war. He sympathised with the popular opinion that Blair had been "echoing Bush's rather crusading attitude" by involving the UK in a war with Iraq.

"Suddenly, his religious convictions became awkward and embarrassing for him and embarrassing for everybody," Dr Williams added.