The Syrian government has suffered its highest ranking defection since the uprising against President Bashar Assad began a year ago.
Deputy Oil Minister Abdo Hussameldin quit his post, saying he could not go on “serving the crimes of this regime”.
A UN team lead by humanitarian chief Valerie Amos visited the Baba Amr district of Homs yesterday.
Amos said the besieged neighbourhood had been left “pretty devastated” by weeks of shelling.
The United Nations estimates more than 7,500 civilians have died in Syria over the past 12 months.
China’s envoy to Syria met with government officials earlier on Thursday to seek an end to the bloodshed.
Beijing has been accused of abetting the violence by blocking two UN resolutions on Syria.
Lu Huaxin said his visit to Damascus was to promote talks between the oppostion and the Assad regime.