International mediator Kofi Annan responded to reports from opposition activists in Syria on Monday that said Syria's regime was using heavy weaponry to attack rebel held positions, resulting in the deaths of at least 74 people.

In a statement released through his spokesman, Ahmad Fawzi, Annan said he was "gravely concerned by the latest reports of violence coming out of Syria and the escalation of fighting by both government and opposition forces."

According to the activists, the deaths occurred mostly in Homs and al-Heffah.

UN monitors in Syria reported Monday that Syrian helicopters were firing on two towns north of Homs. Sausan Ghosheh, a spokeswoman for the observer mission, said "UN observers reported heavy fighting in Sastan and Talbiseh [north of Homs] with mortar shelling as well as firing from helicopters, machine guns and smaller arms."

This marks the first time UN observers in Syria have commented on helicopter attacks, which are believed to take place frequently.

Hague sees terrorist influence

The violence is the latest indication that Annan's proposed peace plan, which was initially agreed to by both sides in the Syrian conflict, is not being put into practice. Complicating matters, according to British Foreign Secretary William Hague, could be the increasing influence of terrorist organizations in Syria.

"We also have reason to believe that terrorist groups affiliated to a-Qaeda have committed attacks designed to exacerbate the violence, with serious implications for international security," he said in an address to parliament in London on Monday.

Hague also said that while he did not want to see Annan's peace plan fail, there could not be an "open-ended commitment" and said if the plan failed, "we would have to consider other options for resolving the crisis. In our view all options would then be on the table."

Germany officially rejects military intervention

Meanwhile, Germany's defense minister on Monday rejected the suggestion that military intervention was the way to go in efforts to bring an end to the fighting in Syria.

In an interview published in the Monday edition of the daily newspaper Tageszeitung, Thomas de Maiziere lamented that “the continued waffling by people who bear none of the responsibility creates expectations in regions like Syria, thereby causing terrible disappointment.”

De Maiziere added that he found it "hardly bearable that some coffee house intellectuals call for the deployment of soldiers in the world without being accountable for it."

The defense minister's comments came a day after his counterpart at the foreign ministry expressed similar sentiments.

Foreign Minister Guido Westerwelle told the Sunday paper Welt am Sonntag that those who demand a military response must be fully aware of the risks. Westerwelle added that giving up on a political solution to the Syrian conflict would amount to giving up on the people of Syria.

Dissenting opinion

However, for the first time on Monday, one prominent parliamentarian from Chancellor Angela Merkel's center-right coalition said he wouldn't rule out the use of force.

"In my opinion, the military option cannot be excluded," Philipp Missfelder told Deutsche Welle in an exclusive interview.

The foreign policy spokesman for the parliamentary bloc of Merkel's Christian Democratic Union and the Christian Social Union also described international envoy Kofi Annan's peace plan for Syria as having "failed," something he described as "very regrettable."

Missfelder said that the international community needed to increase the pressure on Syrian President Bashar al-Assad "within the framework of a UN mandate," something that would "make clear that we mean business."

Missfelder's comments came amid growing frustration in the international community over their inability so far to stop the fighting in Syria.

mz,pfd/msh (AP, dpa, AFP, Reuters)