The Israeli Prime Minister has written to the families of victims of terror as a group launched an appeal with Jerusalem's High Court of Justice to cancel the planned prisoner swap.

Benjamin Netanyahu, whose older brother was killed during the raid on Entebbe in 1976, said he understood and knew the pain of bereaved families.

He said that the decision to bring home captured soldier Gilad Shalit at the price of releasing more than 1,000 Palestinian prisoners early was "among the most difficult" that he had ever made.

"I know that you have a heavy heart and that your wounds have been opened anew these past days; that your thoughts are not at ease," he said.

"I know that the price is very heavy for you. I understand the difficulty to countenance that the evil people who perpetrated the appalling crimes against your loved ones will not pay the full price that they deserve."

But he said that as Prime Minister he had to take responsibility for bringing home "every soldier who is sent to protect our citizens".

"When I went off to fight in the name of the state of Israel, I knew always: the state of Israel does not abandon its soldiers and citizens," he said.