A senior Syrian government official announced his defection from the regime of President Bashar al-Assad early Thursday, while government forces continued attacks on rebellious areas, according to the opposition.
In Geneva meanwhile, a United Nations official said the agency was preparing emergency food aid for up to 1.5 million Syrians, dpa reported.
Around 90 days' worth of food and other aid should be stored in the region, said John Ging, the crisis reaction chief of the UN Office for the Coordination of Humanitarian Affairs.
But more material would likely be needed in the future, Ging told a meeting of aid organizations.
Abdu Hossam al-Deen, an aide to the oil minister, said in footage posted on YouTube early Thursday that he had quit his post to join the "Syrian revolution," becoming the most senior civilian official to defect since the pro-democracy revolt started in March 2011.
"I announce (that I am) joining the revolution of these brave people who will not accept humiliation despite the brutality exercised by the regime and its loyalists to suppress the people's demands for freedom and dignity," he said.
Hossam al-Deen, 68, added that he had also decided to quit the ruling Baath Party, although he said he was aware that al-Assad's regime would hunt for his family.
"I do not want to be part of the regime's crimes," he said.
Syrian state media and officials did not comment on his defection.
However, an Arab diplomat in Beirut told dpa that the dissident was a "low-key" official and that his defection was not a major step that would "shake the regime."
A Syrian activist said that Hossam al-Deen had spent few days in the Lebanese capital Beirut before leaving for a third country "because it is safer for him and his family."
"Lebanon is no longer a safe place for Syrian defectors or activists, as the Syrian regime has many agents in this country," Amar al-Halabi, a Syrian activist based in Beirut, told dpa.
Some 200 personnel of the Syrian army defected Thursday in Reef Damascus, a residential area close to the capital, according to opposition activists. The news could not be independently verified.
Meanwhile, United Nations humanitarian chief Valerie Amos met in Syria with top government officials for talks on improving the health and education situation in the country.
During separate talks with the ministers of health and education, Amos expressed UN readiness to help rebuild schools damaged in the violence, a Syrian journalist said.
She also called on Syrian authorities to give aid workers access to devastated areas, said the journalist, who asked not to be named.
Amos said she was devastated by the scale of destruction she had seen on Wednesday in the rebel Baba Amr district in the central province of Homs.
A UN delegate accompanying Amos told dpa that Baba Amr looked like a "ghost town."
"There were no people. Only rubble and silence," the delegate said.
Baba Amr was the target of government shelling attacks for almost a month before regime troops captured it last week, according to the opposition.
Government forces killed at least 10 people in rebellious areas near Damascus and in the northern province of Idlib on Thursday, activists said.
The troops killed seven and arrested more than 40 men when they raided Reef Damascus on the outskirts of the capital, activists in the area said.
Three others, including a child, were killed by government gunfire in the village of Khan Shaykhoun in Idlib near the border with Turkey, the Britain-based Syrian Observatory for Human Rights said.
In Cairo, meanwhile, the Arab League-United Nations envoy to Syria, Kofi Annan, said he was opposed to a military solution and preferred a diplomatic way out of the Syrian crisis.
The former UN chief added that his upcoming mission to Syria aimed to end the violence there, allow in humanitarian aid and work towards a political solution.
Annan, who was speaking after talks with Arab League chief Nabil al-Arabi, is expected to hold talks in Damascus on Saturday.
A Syrian official, who spoke to dpa on condition of anonymity, said his country was ready to cooperate with all missions.
"We want to show the world that reports claiming government troops are killing the Syrian people are untrue," he said.
The UN has put the number of people killed in Syria's conflict at well over 7,500 in the last 11 months. The death toll includes some 500 children.