Syria has suffered great losses of human lives and in economy as it struggles to calm a months-long unrest starting last March.

Despite the lack of reliable figures on the overall toll, different parties have been constantly rolling out casualty reports on waves of violence recently.

At least four people, including two law enforcement personnel, were shot dead by armed groups in central province Homs and southern city Daraa on Thursday.

An officer and five soldiers were killed Monday in a grenade attack at a checkpoint to the southwest of Damascus and a number of military personnel were killed in Homs by "terrorists" on the same day.

The Syrian government said in December before the arrival of Arab League (AL) monitors that more than 2,000 army and security personnel were killed.

The United Nations puts the overall toll in Syria at more than 5,400, with at least 400 killed since the observers arrived.

In term of economic losses, Syrian Oil Minister Sufian Allaw said the country has lost more than $2 billion in oil revenue since September 1 as a result of import bans by the United States and the European Union.

The oil embargo has caused a drop in production of 150,000 barrels, or 15 million dollars, a day, he told reporters.

The unrest, combined with Western sanctions, has driven the value of the Syrian pound down 50 percent on the black market, exchange dealers said.

As the mandate of Arab monitors expires Thursday evening, violence shows no sign of abating.

Qatar, which leads the AL committee on Syria, said the mission has failed. Qatar Emir Sheikh Hamad bin Khalifa al-Thani proposed sending in Arab troops to Syria, only flatly rejected by the Syrian government.

In a statement in response to the proposal, the Syrian Foreign Ministry said Syria "rejects all kinds of foreign intervention in its affairs, under any title, and would confront any attempt to infringe upon Syria's sovereignty and integrity of its territories."

The proposal is the first by an Arab leader to publicly suggest military intervention in Syria and has not been echoed by any other members of the Arab League.

Head of the Arab observer mission in Syria Moustafa al-Dabi arrived in Cairo to submit his report to Arab foreign ministers at their upcoming meeting on Sunday. The ministers will decide whether to seek agreement from Damascus to extend the mission for another month.

About 120 AL monitors were deployed in Syria on December 26 to verify whether an Arab peace plan was working.

Also on Thursday, a senior NATO official denied the alliance has any intention of direct military intervention in Syria.

"There is no planning and we are not thinking about an intervention," General Knud Bartels, head of NATO's Military Committee, said after a two-day meeting of NATO military chiefs.

He said nations from NATO's Mediterranean Dialogue, a forum which gathers Algeria, Egypt, Israel, Jordan, Mauritania, Morocco and Tunisia, expressed concerns about the upheaval in the region, but "there was no discussion at all of a military intervention."

NATO has played a key role in helping topple former Libyan leader Muammar Gaddafi last year.