Palestinian Prime Minister Ismail Haniyeh on Sunday said plans by Chairman Mahmoud Abbas to hold a referendum on a plan that implicitly recognizes Israel are illegal. The statement was the strongest sign yet that Hamas will not give in to Abbas' ultimatum to accept the plan or face a referendum. Abbas has given Hamas until Tuesday to accept the plan. "The local law does not permit holding referendums on the Palestinian law," Haniyeh told reporters. However, he said he would try to continue a dialogue with Abbas over the plan.