A letter from Israeli Prime Minister Benjamin Netanyahu on the stalled peace process doesn't address key issues hindering talks, the Palestine Liberation Organisation said on Sunday.

Speaking after a meeting of the PLO's executive committee, secretary general Yasser Abed Rabbo said the Israeli premier's message contained no answers to the questions posed in a letter by Palestinian president Mahmud Abbas last month.

"The Israeli message did not contain clear answers on the central issues hampering the resumption of negotiations, foremost among them the need to halt settlement activity," he said in a statement read to reporters.

Netanyahu's letter was delivered to the Palestinians on Saturday by Israeli envoy Yitzhak Molcho, though no details of the document were made public.

Abbas on April 17 sent a letter to Netanyahu asking Israel to outline its position on four key issues: the principle of a two-state solution based on pre-1967 lines, halting settlement activity, releasing all Palestinian prisoners and revoking all decisions that undermine bilateral agreements since 2000.

But in its response, the PLO accuses Netanyahu of failing to address those questions in his exchange of letters with Abbas, which is the latest attempt to kickstart direct negotiations on hold since 2010.

In January, negotiators from both sides held five exploratory meetings in a bid to find a way to resume dialogue, but they ended inconclusively.

The last time both sides held direct negotiations was in September 2010, but they soon broke down over the issue of settlement construction.

The Palestinians say they will not hold negotiations while Israel builds on land they want for their future state, but Israel says it wants talks without preconditions, and accuses the Palestinians of holding up a return to talks.

Abed Rabbo said the executive committee also expressed support for Abbas's decision to devote his meeting with Molcho on Saturday to discussion of the fate of some 1,550 Palestinian prisoners currently on hunger strike.

"The executive committee affirmed its support for the position expressed by president Mahmud Abbas during his meeting with the Israeli envoy on the need for the release of prisoners and the end to their suffering," Abed Rabbo said.

The prisoners, including two who entered their 75th day without food on Sunday, are seeking improved prison conditions and an end to both solitary confinement and administrative detention orders, which allow detention without charge.