An explosion followed by an exchange of fire with rebels in Damascus province on Thursday left at least 21 members of Syria's elite Republican Guards unit dead, a watchdog said.

The Syrian Observatory for Human Rights had reported an earlier toll of 18 from the violence in Qudsaya, west of the capital, but revised it upwards.

Turkey pounded Syrian targets early on Thursday, killing several soldiers, in reprisal for deadly cross-border fire that has sharply escalated tensions in the tinder-box region.

In Ankara, the Turkish parliament met behind closed doors in an emergency session to consider the government's request to authorize Ankara to conduct cross-border military operations inside Syria.

Prime Minister Najib Miqati did not hold talks in New York with Syrian Foreign Minister Walid al-Muallem, reported al-Joumhouria on Thursday.

Al-Liwaa newspaper had reported on Wednesday that the two officials had met during their visit to New York to attend the United Nations General Assembly.

The Nabi Sheet explosion in a Hizbullah arms depot on Wednesday demonstrated the danger the party's weapons pose to Lebanon, reported al-Joumhouria newspaper on Thursday.

March 14 sources noted to the newspaper that the Hizbullah sought to demonstrate the power of the blast through the damage it caused, which is an indication that the explosion was deliberate.

Turkey's government will seek approval from parliament for cross-border military operation in Syria "when deemed necessary", at a special session Thursday morning, the private NTV television reported.

The decision came after Prime Minister Recep Tayyip Erdogan held a three-and-half hour cabinet meeting following Syrian shelling that killed five Turkish nationals in a border town.

The rebel Free Syrian Army on Wednesday warned Hizbullah of a “severe and earthshaking retaliation,” after the Syrian opposition said Tuesday that a Hizbullah commander and several fighters were killed inside Syria.

“We promise the Hizbullah members who are deployed in Syria that they will face a severe and earthshaking retaliation over their interference in the Syrian affairs and aiding the regime of President Bashar Assad to kill the Syrian people,” the Joint Command of the Free Syrian Army in Syria said in a statement.

The Hamas movement in Gaza expressed "deep regret" on Wednesday over a commentary aired by Syrian state television that criticized the group's leader Khaled Meshaal.

The remarks, broadcast on Syrian state television on Tuesday night, came after Meshaal attended a conference on Sunday of Turkey's ruling Justice and Development party, which has been a staunch of the Syrian opposition.

Turkey on Wednesday shelled Syria in retaliation for cross-border fire that killed five Turkish nationals, the prime minister's office said in a statement.

"Our armed forces in the border region immediately retaliated against this heinous attack... by shelling the targets spotted by radar," it said.

The authority charged with following up on the case of the death of Sheikh Ahmed Abdul Wahed and his companion Sheikh Mohammed Merheb demanded on Wednesday that the case be reopened following recent revelations that the Syrian regime was involved in the crime, reported the National News Agency.

The authority demanded from President Michel Suleiman and Prime Minister Najib Miqati to reopen the case and refer it to the judicial council.

In the courtyard of a school in northern Lebanon refugee children from neighboring Syria clamor to grab one of the flags of their country's rebellion being handed out before they enter the classroom.

Rich or poor, from all over Syria, they are among 1,500 Syrian primary school children who began the new academic year studying in Lebanese schools after their families fled the bloodshed at home, and the flag is a poignant symbol for them.