Fighting raged across Syria with activists claiming more than 140 people killed on Monday alone, as Lakhdar Brahimi angered both the Syrian regime and opposition with some of his first comments as the new UN and Arab League peace envoy.

Many of the latest casualties were from the southern province of Daraa, birthplace of the Syrian uprising, according to the Syrian Observatory for Human rights, a London-based opposition group.

The group said that a Japanese female journalist was killed on Monday covering clashes in Syria’s Aleppo, while three other reporters from Turkey, Lebanon and another Arab country went missing.

Activists said the heavy shelling on Daraa took place because government forces believe that some high-profile defectors, including possibly Vice President Farouk al-Sharaa, may be hiding there.

Mr Al-Sharaa’s office has officially denied opposition reports that he has defected, and Syria’s state news agency has denied reports that Foreign Minister Walid al-Moallem had been named to replace Mr al-Sharaa.

Former premier Riad Hijab, another high-profile defector, is believed to have fled into Jordan from the same area.

The surge in violence took place as the last international observers were on their way out of Syria, after the UN Security Council declined last week to extend their mandate, which ended on Sunday.

The observers were sent in April to Syria to monitor a UN-brokered ceasefire that never held. The UN plans to maintain a political liaison office in Damascus to support mediation efforts after veteran diplomat Mr Brahimi takes his post as Syria’s new international envoy this week.

In Washington, US President Barack Obama issued a “red line” warning to Syria on chemical weapons, saying there would be “enormous consequences” if the US detects any movement of the Damascus regime’s unconventional arms. That would “change my calculus,” he said.

Mr Brahimi, an Algerian who replaces Kofi Annan, irked both the opposition and the regime by suggesting that a civil war was underway in Syria, and that he did not know when President Bashar al-Assad might step down.

“To speak of civil war in Syria contradicts reality and is found only in the heads of conspirators,” the Syrian Foreign Ministry said in a statement carried by the official news agency SANA.

Since the Syrian uprising erupted in March 2011, Damascus has insisted that it is fighting “armed terrorist groups” allegedly seeking to destabilize Syria with backing by the West and Gulf states.

The Syrian opposition has demanded an apology from Mr Brahimi for being non-committal over al-Assad’s fate.

“The revolutionary Syrian people were shocked and dismayed by Brahimi’s statements,” the opposition Syrian National Council said.

”... We call on the international envoy - who has not yet consulted with any Syrians on his appointment or his mission - to apologize to our people for taking this unacceptable position.” Mr Brahimi later told Dubai-based broadcaster Al-Arabiya that his earlier remarks had been misinterpreted and that he had called the Syrian opposition to apologize.

“My mission will not be easy,” Mr Brahimi, 78, told Al-Arabiya.

Before heading to UN headquarters in New York, Mr Brahimi said after meeting with French President Francois Hollande in Paris that France was “an important country in everything that relates to Syria.” Mr Hollande assured Mr Brahimi of French support, urged him to “do everything to first obtain a cessation of violence” and reiterated France’s position that there could be “no political solution without the departure of Bashar al-Assad” in Syria.

On Wednesday, a US diplomat is to lead a military and intelligence team to set up a US-Turkey working group on contingency plans for Syria. US acting assistant secretary of state Beth Jones is to lead the team, with tasks including forging contingency plans in case the al-Assad regime deploys chemical weapons.

In a separate incident, a car bomb exploded near a police station killed eight people and wounded 50 others Monday night in south-eastern Turkey near the Syrian border, Turkish media reported.

There was no immediate claim of responsibility for the blast in Gaziantep, where as many 70,000 refugees are living in camps after fleeing Syria.

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