"His appointment is not acceptable to Hamas nor to the Palestinians. He will not do anything to support the Palestinian interests but will do everything to support the Israeli occupation," he said.
On a trip to Amman, Mahmoud Abbas, the Palestinian president, greeted news of the appointment of Blair and pledged to work with Blair towards achieving peace, an official said.
"President Abbas welcomes the nomination of Mr Blair as envoy of the quartet," Saeb Erakat, the chief Palestinian negotiator, said.
"The president, who was consulted on the matter, has given the assurance that he will work with Mr Blair to arrive at a peaceful solution on the basis of two states," Erakat said.
He also said that Abbas was confident Blair’s appointment "will help boost the institutions of the Palestinian Authority and aid economic growth" .
Meanwhile, George Bush, the American president, welcomed his closest ally to his new post.
"I am pleased that this capable man has agreed to continue his work for peace in the Middle East," Bush said in a statement.
"Tony will help Palestinians develop the political and economic institutions they will need for a democratic, sovereign state able to provide for its people and live in peace and security with Israel," Bush said.
Reaction from Russia was more guarded with Sergei Lavrov, the foreign minister, saying that Moscow would support Blair's appointment if the other members of the quartet were in favour.
"If the whole of the quartet is in favour, we are going to welcome Tony Blair's contribution to efforts to normalise the situation in the Palestinian territories," Lavrov said.
In Paris, Nicolas Sarkozy, France’s president applauded the appointment of Blair, lauding his "qualities as a statesman and his knowledge of the region".
Meanwhile back home, Gordon Brown, Britain's new prime minister, said he was "delighted", adding that his predecessor was "exceptionally well placed" to take on the role.