The Israeli Supreme Court has upheld the government's refusal to allow supplies of fuel and electricity to the Gaza Strip, a court spokeswoman has announced.
Israeli human rights groups had challenged the sanctions, which Israel says are aimed at halting ongoing rocket fire by Gaza militants.
Palestinian officials say the cutbacks have harmed Gaza's already impoverished residents by causing power shortages and crippling crucial utilities.
Israel supplies all of Gaza's fuel and over two-thirds of its electricity, and has reduced but not halted the shipments.
Israel was the subject of much international condemnation following its decision to impose its blockade.
Hamas Islamists, who seized control of Gaza in June after routing Abbas's secular Fatah forces, blasted open the Egyptian border last week in defiance of the Israeli blockade, letting Gazans pour into Egypt to stock up on essential goods.