Syrian leader President Bashar Assad is losing the fight against rebel forces and must be made to leave as quickly as possible, French President Francois Hollande said Friday.

"On the ground, the war is now turning against Assad and we should set ourselves this objective -- make Assad leave as quickly as possible," Hollande said as he went into a meeting of EU leaders where the Syrian conflict will be discussed.

The families of the Lebanese fighters who were killed in Syria's Tall Kalakh recently warned of staging rallies across Lebanon on Monday if the authorities failed to retrieve the bodies of the men over the weekend, demanding the expulsion of Syrian ambassador to Lebanon Ali Abdul Karim Ali.

“If we don't retrieve the corpses by Sunday we will invade the streets,” head of committee formed to follow up the case of slain Tall Kalakh fighters Sheikh Mohammed Ibrahim told reporters.

Russia said on Friday that it had not changed and would not change its controversial stance on Syria, after a top Russian diplomat said the defeat of the Syrian regime was possible.

"We have never changed our position (on Syria) and we never will," foreign ministry spokesman Alexander Lukashevich said.

The jihadist al-Nusra Front claimed on Thursday that two of its men were responsible for a deadly suicide attack on the Syrian interior ministry the day before, via its official Twitter account.

"Thank God, we targeted the interior ministry building in Kfar Sousa district in Damascus at 5:30 pm on Wednesday, December 12," the extremist group Tweeted, adding that fighting had erupted inside the ministry.

Lebanese lawyer Rashad Salameh agreed on Thursday to being appointed on Syria's behalf to prosecute former Premier Saad Hariri, Mustaqbal MP Oqab Saqr, and Syrian opposition member Louay al-Meqdad, reported the Central News Agency.

Widely-informed sources told the news agency that Salameh accepted the appointment on behalf of the Syrian state in its case against all those who armed the Syrian revolution.

Syrian President Bashar Assad's regime appears likely to fall within weeks, a senior minister in Iraq, whose country has avoided publicly taking sides in Syria's conflict, told AFP on Thursday.

"There is a real acceleration regarding the international community focusing on Syria... real concern about the using of chemical weapons," Finance Minister Rafa al-Essawi said on the sidelines of a meeting with the International Monetary Fund in Amman.

"I am not a mercenary," said a Spanish former air force officer who left family and a spiraling economic crisis behind at home to travel to Syria and train insurgents fighting troops loyal to President Bashar Assad.

"I could see on television what was happening in Syria... I've never been able to handle watching children get killed without reacting," said Luis Munar, who entered Syria via the Bab al-Hawa border crossing on the Turkish frontier.

A former Syrian officer who served in a battalion specializing in surface-to-surface missiles told AFP on Thursday regime forces had fired Scuds three days ago, but the government has denied this.

First Lieutenant Aaraba Idriss said he is still in contact with officers and members of his former Battalion 57, part of Brigade 155, despite defecting 10 months ago.

Syrian President Bashar Assad's regime is approaching collapse and he should take steps to begin talks on a political transition, NATO head Anders Fogh Rasmussen said Thursday.

"I think the regime in Damascus is approaching collapse ... it is only a question of time," Rasmussen said, adding that Assad should "initiate a process that leads to the accommodation of the legitimate aspirations of the Syrian people."

Pakistan has withdrawn its diplomatic staff from Syria due to deteriorating security in the country, the foreign ministry said Thursday.

"We have temporarily withdrawn our diplomatic staff, including the ambassador, from Syria and they have all returned home," ministry spokesman Moazzam Ahmed Khan told Agence France Presse after his weekly press briefing.