A Palestinian group allied with the Syrian regime said Monday it would retaliate if the country was attacked, as Western nations weigh military action after alleged chemical weapons use near Damascus.

"The regional interests of those who participate in aggression against Syria will be legitimate targets," Anwar Raja, a spokesman for the Popular Front for the Liberation of Palestine-General Command (PFLP-GC) told Agence France Presse in Damascus.

A successful outcome to the U.S.-brokered negotiations between Israel and the Palestinians would be like a "thunderbolt" for peace in the crisis-ridden Middle East, French Foreign Minister Laurent Fabius said Saturday.

"Even if we speak of other neighboring countries -- the dramatic conflict in Syria, Lebanon, Egypt -- the fact remains that the Israeli-Palestinian issue is one of the issues, perhaps the central one, for the region," he said in the West Bank city of Ramallah, after meeting Palestinian president Mahmoud Abbas.

French Foreign Minister Laurent Fabius said on Saturday that all indications show the Syrian government was behind a "chemical massacre" near Damascus that the opposition claims killed hundreds of people.

"All the information at our disposal converges to indicate that there was a chemical massacre near Damascus and that the Bashar regime is responsible," Fabius said on a visit to Ramallah in the West Bank.

French Foreign Minister Laurent Fabius will visit Israel and the Palestinian territories this weekend to encourage recently resumed peace talks, his office said Friday.

Fabius will meet Palestinian president Mahmoud Abbas and prime minister Rami Hamdallah in Ramallah on Saturday.

A Palestinian from Gaza who was snatched from Ukraine and is being held in an Israel prison has begun refusing food, a prison spokeswoman said on Thursday.

Dirar Abu Sisi "was on the third day of a hunger strike, following which all his personal items and electric appliances were removed from his cell, except for a fan," Israel Prison Service spokeswoman Sivan Weizman told Agence France Presse.

Palestinian security services have arrested an Islamist sympathizer in the West Bank for selling perfume named in honor of Egypt's ousted president Mohammed Morsi, family members said on Thursday.

Islambuli Badir, a 36-year-old member of Islamist movement Hamas, was arrested during a raid on his perfume shop in the town of Tulkarem, his brother Abdel Fattah Badir told Agence France Presse.

The Palestinians threatened Wednesday to sue Israel through international bodies if it continues expanding settlements in the occupied territories, warning it was an issue that could torpedo fledgling peace talks.

"These are not just dots on a map," PLO executive committee member Hanan Ashrawi said of more than 2,000 new settler homes which were approved for construction ahead of a resumption of peace negotiations late last month.

Israeli and Palestinian officials held talks in Jerusalem on Tuesday and were to meet again later the same day, Palestinian sources said, just six days after they resumed direct negotiations.

An initial two-hour meeting took place in secret in the morning, with negotiators set to return to Jerusalem's King David Hotel for a "second round of talks" at around 7:30pm (1630 GMT), a senior official said on condition of anonymity.

Egypt briefly reopened the Rafah crossing on Saturday for humanitarian reasons to allow in some 50 people who were stranded in the Gaza Strip, the Hamas interior ministry said.

Egypt had on Thursday announced it was closing "indefinitely" the only crossing -- the only route into the Hamas-ruled coastal enclave that bypasses Israel -- for security reasons a day after deadly violence nationwide.

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.