LONDON (Reuters) - Prime Minister David Cameron's plan to get changes to European Union treaties as part of his renegotiation of Britain's ties with the bloc is "mission impossible", European Council President Donald Tusk told the Guardian newspaper.
Cameron has pledged to reform Britain' EU relationship ahead of a membership referendum by the end of 2017 if he is re-elected in May, and has said he believes treaty change will be needed to adapt rules in areas such as immigration.
"My intuition is that treaty change is close to mission impossible today because it's not only about rationality, about good argument," Tusk told the Guardian.
"We need unanimity between 28 member states, in the European parliament, in 28 national parliaments in the process of ratification. To say that it is a Pandora's Box is too little."
Tusk said he wanted to help Cameron achieve reform but needed to know more details about what Britain wanted to assess whether treaty change was even needed. Other member states did not want discussion of treaty change, he said.
"We need ... a good solution for Cameron and Great Britain under existing law," he said. "We need the United Kingdom in Europe ... And I feel, but it's not my role to decide about it, but I feel that the United Kingdom needs Europe."
(Reporting by Kylie MacLellan; editing by Guy Faulconbridge)