U.N. chief Ban Ki-moon called on Israelis and Palestinians on Friday to overcome "deep skepticism" that he said risked thwarting efforts to reach a peace agreement.

"We must overcome the deep skepticism that comes from 20 years of stalemate," Ban said at a meeting in Jerusalem with Israeli President Shimon Peres.

Almost 80 percent of Israeli Jews believe a peace deal with the Palestinians is impossible, an opinion poll found on Friday, two days after the resumption of negotiations in Jerusalem.

Asked whether "this time, we will reach a final agreement that will put an end to the conflict," 79.7 percent of respondents said no, and just 6.2 percent said yes.

Palestinian president Mahmoud Abbas said Thursday all key issues were discussed at a new round of peace talks with Israel, but he declined to elaborate because of an agreed news blackout.

"We can't speak now about what happened," he told a joint press conference with U.N. chief Ban Ki-moon at his headquarters in the West Bank city of Ramallah.

U.N. Secretary General Ban Ki-moon urged Israelis and Palestinians Thursday to have "patience" with their peace talks so that they might have a chance to succeed, state-run Petra news agency reported.

After holding talks in Amman with Jordanian Foreign Minister Nasser Judeh, Ban stressed the U.N.'s support for peace talks between the two sides, which resumed in Jerusalem on Wednesday.

An Israeli organisation said on Thursday that it has secretly flown 17 Yemeni Jews to Israel after evacuating them from the Arabian Peninsula country.

A direct flight from Yemen brought four adults and one child to Ben Gurion airport near Tel Aviv on Wednesday, said Arielle Di Porto, a spokeswoman for the Jewish Agency responsible for Jewish immigration to Israel.

Egyptian authorities have closed the Rafah border crossing with the Gaza Strip "indefinitely" for security reasons after a day of deadly violence nationwide, a security official told Agence France Presse on Thursday.

Hundreds of Palestinian travelers were left stranded on both sides of the crossing, the only gateway into the Hamas-ruled Palestinian territory that bypasses Israel, witnesses said.

Iran said it was "hostile" to Israeli-Palestinian peace talks brokered by the United States, hours before negotiations in Jerusalem were due to kick off on Wednesday.

"Iran is hostile to these negotiations and several Palestinian groups are hostile to them," foreign ministry spokesman Abbas Araqchi told the ISNA news agency.

Israel warned on Wednesday that it might shun a key EU research program unless a compromise is found over the bloc's guidelines which bar funding to Jewish settlement entities.

Its position was spelt out at a meeting with the European Union on the Jewish state's participation in Horizon 2020, the bloc's six-year funding plan for research and innovation, the foreign ministry said.

Tears streamed down Hosni Sawalha's face as he recited from the Koran alongside the graves of his parents, who died while he was in Israeli jail since his teens.

The 40-year-old and his cousin Mohammed Sawalha were released alongside 24 other long-serving Palestinian inmates early on Wednesday, hours before a new round of peace talks with Israel.

Iran's nuclear program was at the center of discussions on Wednesday between U.S. army chief General Martin Dempsey and Israeli Defense Minister Moshe Yaalon, public radio said.

"The Iranian regime is involved in all of the conflicts in the region," the radio quoted Yaalon as saying during talks in Tel Aviv with Dempsey which were also attended by Israeli armed forces chief of staff General Benny Gantz.