The two-state solution is in extremely grave condition, the UN's special coordinator for the Middle East peace process warned in an interview with Haaretz last week.

"The two-state solution is now on life support," Robert Serry said. "This is in fact a critical year. Everyone should know that if we do not provide a credible diplomatic horizon for the two-state solution this might lead to very serious results."

Serry, speaking at the UN's offices in Jerusalem, said he was concerned about the hunger strike by Palestinians imprisoned in Israel and the consequent wave of solidarity demonstrations in the West Bank. "The prisoners issue can always easily lead to worse things," he said, adding that UN Secretary General Ban Ki-moon had "discussed his concern" with Prime Minister Benjamin Netanyahu after Israel's election last month.

The interview took place before Arafat Jaradat died in Israeli custody of unknown causes on Saturday.

Serry said that despite "some remarkable achievements regarding Palestinian state-building" over the last five years, Palestinian Prime Minister Salam Fayyad's "situation has become very difficult."

"Everyone has always assumed that in time, the two channels would merge together," Serry said, referring to Fayyad's state-building efforts and diplomatic negotiations. "This did not happen. Right now, there is no evident political horizon. This cannot go on anymore. The status quo cannot continue because it will only lead to deterioration."

Ever since the UN General Assembly recognized Palestine as a nonmember observer state on November 29, "we are now on 'make or break' time," he continued. "The window of opportunity would not remain open for more than a few months. We can either go forward or slip backwards. There is no other option. The peace process is not a child's toy you can wind up again whenever and as many times you wish. The situation has become too serious for that.

"You [Israelis] no longer have a partner for negotiations for the sake of negotiations with no apparent results. It is particularly important that something fundamental happens on the ground, a change of direction. We need positive steps which would allow state-building - and we mustn't forget Gaza."

Serry said it's important for the UN to maintain communications with Hamas in Gaza. "The PLO is the only legitimate representative of the Palestinian people," he said. "What we do in Gaza is not a recognition of the Hamas government, but it is necessary to maintain contact with Hamas, in particular to protect the integrity of UN operations. There is an informal, quiet dialogue with Hamas.

"I want the Israeli public to know that this dialogue is sometimes helpful for Israelis - for instance when the UN acts in support of Egypt to keep the calm. In October 2011, an Israeli general called me in the middle of the night and asked me to deliver an urgent message to Hamas saying that Israel was not behind an explosion that occurred that day. A week later I understood what was so urgent - when [kidnapped soldier] Gilad Shalit was released.

"This is the longest term in Gaza without rockets being shot," he continued. "What does it mean? That Israel is getting security but in return, needs to take some humanitarian measures. If it will allow unhindered access of constructing materials it will be very helpful."