The Syrian authorities have tightened security measures around government buildings in Damascus for fear of new rebel attacks, a pro-government daily reported on Wednesday.

"Security measures around official buildings and companies," Al-Watan newspaper said.

Syrian warplanes Wednesday blitzed rebel targets around the strategic northern town of Maaret al-Numan while ground forces shelled opposition belts outside the capital Damascus, a watchdog said.

"The Syrian airforce have made no less than six sorties early morning, pounding the villages of Deir Sharqi, Maarhtat and Bsida, east of Maaret al-Numan," which rebels captured a week ago, the Syrian Observatory for Human Rights said.

Turkey's Kurdish rebels will retaliate to any Turkish attacks on Kurds in war-torn Syria, the second in command of the outlawed PKK said in an interview published Wednesday.

"Turkey should stay out of this conflict and stop its scheming," Murat Karayilan, who heads the outlawed Kurdistan Workers' Party (PKK) in the absence of its jailed leader Abdullah Ocalan, told Swiss daily Le Temps.

United Nations and Arab League envoy to end the Syrian crisis Lakhdar Brahimi held talks on Wednesday with senior Lebanese officials on the conflict in the neighboring country, warning the unrest there will inevitably spread to the region.

He hoped that the ceasefire set for the Eid al-Adha holiday “will pave the way for a permanent solution to the crisis.”

Foreign militants fighting in Syria could contribute to an increased "radicalization" of the conflict, members of a U.N. commission investigating rights abuses in the war-torn country said Tuesday.

"The presence of foreign militants, radical Islamists or jihadists, worries us very much," commission head Paulo Sergio Pinheiro told reporters, estimating there were hundreds of foreign combatants on the ground in Syria.

British police on Tuesday charged a man with kidnapping two Western journalists in Syria, one week after he was arrested at London's Heathrow Airport, Scotland Yard said.

Shajul Islam, 26, is alleged to have "unlawfully and injuriously imprisoned" photographers John Cantlie from Britain, and Jeroen Oerlemans from the Netherlands, between July 17 and 26, it said in a statement.

The Syrian government is interested in exploring a ceasefire in the 19-month conflict as proposed by international envoy Lakhdar Brahimi, foreign ministry spokesman Jihad Maqdisi said on Tuesday, as the opposition Syrian National Council said it “would welcome any halt to the killings.”

Maqdisi stressed that for a halt to the violence, the rebels and their backers would need to be involved too.

Syria will hold by-elections on December 1 to fill five seats in parliament, two of which became vacant when sitting MPs defected to the opposition, state news agency SANA said.

"President Bashar Assad has passed a decree calling for the organization of parliamentary elections for December 1 to fill five empty seats," SANA said.

A senior U.S. official will hold talks in Ankara on Tuesday on a range of issues including the Syrian crisis amid heightened tensions between Ankara and Damascus, an embassy spokesman said.

"We continue to consult with our partners in the region including Turkey on a variety of issues related to Syria," U.S. embassy spokesman in Ankara T.J. Grubisha told AFP.

Egypt's Foreign Ministry said on Tuesday that it has asked Syria to clarify circumstances in which three Egyptians were killed in fighting in Aleppo and Homs.

The ministry said it sent an "urgent message" to Damascus demanding an explanation for the death of the men, after Syria said one of them headed an armed group in rural Aleppo.