At least 16 people died in violence across Syria on Sunday, activists and state media said, as the visiting Red Cross chief sought access to those detained in five months of anti-regime protests.
Arab League chief Nabil al-Arabi, meanwhile, said Syria has agreed to host him for a visit which he would probably make this week.
In the latest bloodshed, six soldiers and three civilians were killed when an "armed group" opened fire on a bus in Maharda, central Syria, state news agency SANA reported.
"Nine people, among them an officer, were killed and 17 others wounded this morning in Maharda in an ambush by an armed group who opened fire on a bus carrying soldiers and labourers going to work," it said.
SANA said a security patrol killed three of the assailants.
The Local Coordination Committees (LCC), which groups anti-regime activists on the ground, said security forces shot dead three people in the Khan Sheikhwan area of Idlib province in northwestern Syria.
The security forces encircled hospitals "to prevent the wounded from being brought in for treatment," it charged.
On Friday, SANA said gunmen in Khan Sheikhwan had kidnapped a corporal with Syria's internal security services, Wael Ali.
Omar Idlebi of the Syrian Revolution Coordination Committee, which organises protests, added a woman was shot dead in Maaret al-Numan in an operation to arrest her husband, who was wounded along with three other family members.
International Committee of the Red Cross (ICRC) chief Jakob Kellenberger flew into Damascus on Saturday for talks with President Bashar al-Assad over access to prisoners and areas of unrest.
According to activists, 27 people were killed in operations by the army and security services across Syria on Friday and Saturday.
The latest bloodshed came as European ministers warned of more sanctions in addition to an oil embargo over Syria's defiance of mounting international calls to halt a deadly crackdown on anti-Assad protests.
More than 2,200 people have been killed in Syria since almost daily protests began on March 15, according to the United Nations, while human rights groups say more than 10,000 people are behind bars.
Apart from the oil embargo which went into effect on Saturday, the EU expanded a list of around 50 people, including Assad, targeted by an assets freeze and travel ban.
The ICRC delegation chief in Damascus said Kellenberger would stay in Syria until Monday afternoon and meet with Assad, Prime Minister Adel Safar and Foreign Minister Walid Muallem.
His office said that during a previous visit in June "an understanding was reached" for "enhanced access to areas of unrest, and negotiations would take place concerning ICRC visits to detainees."
Asked about the possibility of visiting detainees, the ICRC delegation chief in Damascus, Marianne Gasser, said: "We are confident that we will be able to start visiting people detained by the interior ministry."
In another opening, Arab League secretary general Arabi, who had said he was ready to visit Damascus a week ago after an Arab League statement which angered Syria, told reporters in Cairo that Syrian authorities now agreed to a visit.
"I will express Arab concerns and I will listen," he said.
Syria said an August 27 statement passed by Arab League foreign ministers on the country's deadly unrest contained "unacceptable and biased language," leaving Arabi to await a green light to visit.
In a diplomatic note seen by AFP, Syria's delegation said the declaration was issued "despite the meeting having closed with an agreement that no statement would be published or statement made to the press."
Damascus said it would act as if the statement had never been published.
Foreign ministers of the 22-member organisation based in Cairo called for an "end to the spilling of blood and (for Syria) to follow the way of reason before it is too late."
They also called for respecting "the right of the Syrian people to live in security and of their legitimate aspirations for political and social reforms."