British Defence Secretary Liam Fox has questioned the qualifications of Middle East envoy Tony Blair, who is already facing criticism from the Palestinians over his peace role.

Fox spoke at a fringe event at the governing Conservative party conference late Tuesday, ahead of a meeting of the members of the Middle East Quartet in Brussels on Sunday to discuss how to revive Israeli-Palestinian peace talks.

"Given his record as prime minister of the UK, I'm not exactly sure what the great qualities are of Tony Blair to make him such an exceptional international statesman," Fox said, according to the PoliticsHome website.

Blair, who was Labour prime minister between 1997 and 2007, led Britain into the controversial US-led war in Iraq in 2003, as well as sending troops into Afghanistan as part of the NATO-led operation in 2001.

He was appointed envoy for the Quartet comprising the United States, United Nations, European Union and Russia in 2007 but his role has come under increased scrutiny recently as efforts for peace have stalled.

On Saturday, Palestinian negotiator Nabil Shaath renewed Palestinian charges of pro-Israeli bias against Blair, although he said they had not submitted any official request for him to be removed from his post.

"His major worry is not to anger the Israelis, and therefore he ended just selling their programmes, their projects, and if he does that his usefulness would be extremely limited, to us," Shaath said.

"We have not as yet submitted any official request to take him away. We'd rather discuss this with the Quartet whenever we have a chance to meet the Quartet."