Israel warned the Palestinian Islamist movement Hamas on Sunday it will pay a "heavy price" for the latest barrage of rocket attacks into the Jewish state and that the conflict could escalate.

"Hamas is responsible for the rocket fire and all other attempts to harm our soldiers and civilians, even when other groups participate. And it is Hamas that will pay the heavy price," Defense Minister Ehud Barak said.

Saudi King Abdullah is to undergo another operation on a back problem in a Riyadh hospital this week, the palace announced on Sunday.

Medical tests "showed the presence of a slackening ligament in the upper back," it said in a statement carried by the official news agency SPA.

The trial of late strongman Moammar Gadhafi's last prime minister, Al-Baghdadi al-Mahmoudi, is to open in the Libyan capital on Monday, the public prosecutor's spokesman said.

"Al-Baghdadi al-Mahmoudi will appear tomorrow (Monday) on the occasion of a first case" against him, Taha Baara said, adding that Mahmoudi faces charges of "prejudicial acts against the security of the state."

Israeli troops fired warning shots into Syria Sunday, the army said in a statement, in what public radio said was the first Israeli fire directed at the military in the Golan Heights area since the 1973 war.

"A short while ago, a mortar shell hit an IDF post in the Golan Heights adjacent to the Israel-Syria border, as part of the internal conflict inside Syria. In response, IDF soldiers fired warning shots towards Syrian areas," the army said in a statement.

Possible clean-up activities at an Iranian military base where the U.N. atomic agency wants to probe evidence of suspected nuclear weapons research are "ongoing," the watchdog's head said on Sunday.

International Atomic Energy Agency (IAEA) chief Yukiya Amano nevertheless expressed guarded optimism on a visit to Baghdad about talks with Iran next month, ahead of the expected release on Friday of the IAEA's latest report on the Islamic republic's controversial nuclear activities.

Parliament has launched a probe into the death in detention of an Iranian blogger and will make its report public, the ISNA news agency on Sunday cited deputy speaker Mohammad Hassan Abutorabi as saying.

Opposition activists say blogger Sattar Beheshti, 35, was tortured to death in prison for criticizing Iran's regime on the Internet.

Iraqi authorities executed 10 men on Sunday, a spokesman said, bringing to 129 the number of people put to death this year, defying international calls for a halt to Baghdad's use of capital punishment.

The mass executions were the first in around a month in Iraq, which has been roundly condemned by European governments and international human rights organizations for its use of the death penalty.

The Palestinians will submit a bid to the General Assembly for non-state membership of the United Nations later this month, President Mahmud Abbas said on Sunday.

"We're going to the United Nations in November 2012, not 2013, or 2014," Abbas said at an event commemorating the eighth anniversary of the death of former president Yasser Arafat.

Palestinians are coordinating with Russia, as well as Swiss and French experts, on the exhumation of late President Yasser Arafat, Palestinian President Mahmud Abbas said Sunday.

Arafat died in a French military hospital near Paris on November 11, 2004 and French experts were unable to say what had killed him, with many Palestinians convinced he was poisoned by Israel.

Israel is "prepared to escalate" its response to a flare-up of violence along its border with the Gaza Strip, Israeli Prime Minister Benjamin Netanyahu warned on Sunday.

"The world must realize that Israel won't sit by idly in the face of attempts to attack us. We are prepared to escalate our actions," he said at the start of his weekly cabinet meeting.