The UN's humanitarian chief has arrived in Syria to urge the government to allow aid access to its battle-scarred cities.
Valerie Amos met the Syrian foreign minister in Damascus and is now on her way to the violence-hit city of Homs.
Syria has said it will not allow an International Committee of the Red Cross (ICRC) aid convoy into the Baba Amr area because of security concerns.
The US president has described the situation in Syria as "heartbreaking".
The UN-Arab League envoy to Syria, Kofi Annan, is also due to visit Syria in the coming days.
Syrian Foreign Minister Walid Muallim told Baroness Amos that the government would co-operate with her team and was trying to help civilians, according to Syrian state news agency Sana.
The UN says more than 7,500 people have died as a result of the violence in Syria over the past 12 months.
Nine people were killed on Wednesday, of whom four were in Idlib, three in Homs and one each in suburbs of Damascus and Aleppo.
Meanwhile, Air France announced on Wednesday that it was stopping all flights to Damascus until further notice.
The airline currently operates three flights a week to the Syrian capital but has suspended the service in light of the worsening security situation.
Baroness Amos has said that her aim was to "urge all sides to allow unhindered access for humanitarian relief workers so they can evacuate the wounded and deliver essential supplies".
The UN refugee agency (UNHCR) said more than 1,500 people, mostly women and children from in and around Homs, have crossed the border into Lebanon to escape the violence.
The ICRC - along with the Syrian Red Crescent - has been waiting since Friday to enter Baba Amr, the worst affected district of Homs.
Baroness Amos is travelling to the city, Syria's third largest, with the Red Crescent and is scheduled to meet with the head of the Syrian Red Crescent, Abdulrahman Attar, on Thursday.
Unconfirmed reports from activists in Syria say troops and tanks are now making their way to the northern province of Idlib.
The BBC's Jim Muir, in neighbouring Lebanon, says there are fears Idlib could be the next major flashpoint as international attention focuses on Homs.
State television has shown images of a massive clean-up operation in Baba Amr, with bulldozers and soldiers clearing the streets, and guns and grenades laid out on the road.
On Tuesday, it broadcast pictures of dozens of men, women and children returning on foot to Baba Amr passing bullet-pocked and damaged buildings, days after the rebel fighters fled nearly a month of shelling.
Our correspondent says the ICRC is being kept waiting on the fringes of Baba Amr on the pretext that there is a security risk while an operation to sanitise the area takes place.
The Syrian government's message, he says, is that the outside world is not needed.
Activists said an extended family of 17 people, including a one-year-old child, was massacred in their home with knives on Tuesday, killed by security forces and pro-government militiamen. The deaths have been blamed on rebels by a television station close to the Syrian government.
International media organisations are heavily restricted in Syria, making it impossible to verify the claims of either side.
Mr Obama has said that unilateral US military intervention in the country would be a mistake.
He said President Bashar al-Assad would fall, as other dictators had fallen, but the US would try to achieve this by working to isolate Syria.
"The notion that the way to solve every one of these problems is to deploy our military, that hasn't been true in the past, and it won't be true now," said Mr Obama.
The US says it is proposing a new UN Security Council resolution demanding an end to violence in Syria.
Ambassadors from the five permanent members of the council held talks at UN headquarters on Tuesday, along with Morocco, representing Arab countries.
The US draft demands "unhindered humanitarian access" and "condemns the continued widespread, systematic, and gross violations of human rights and fundamental freedoms by the Syrian authorities and demands that the Syrian government immediately put an end to such violations," Reuters news agency reports.
One UN representative quoted by Reuters, Indian Ambassador Hardeep Singh Puri, said the council should not take any steps until after it hears back from Baroness Amos' and Mr Annan's visits.
Russia and China have vetoed two previous resolutions, saying they were unbalanced and only demanded the government stop attacks.
Russia has made it clear that its position on Syria has not changed since Vladimir Putin was re-elected as president at the weekend.
China, however, announced on Wednesday that it had already removed most of its workers from the country.
"I can tell you most Chinese workers have been withdrawn from that country to China,'' Chinese Commerce Minister Chen Deming said, adding that only 100 Chinese citizens were left in Syria to protect assets and projects.