Syria on Saturday vowed an "iron fist" response to a bombing in the capital Damascus that killed 26 people the day before, dpa reported.
"We will hit back with an iron fist at anyone who tries to tamper with the security of the country or its citizens," said Interior Minister Ibrahim al-Shaar on state television.
A bomber blew up himself Friday in the Maidan district of central Damascus, also wounding more than 60, the government said.
On Saturday, thousands of mourners attended the funerals of the victims.
"May God protect Syria and its sovereignty," chanted the mourners, as they walked in a funeral procession in central Damascus, said witnesses.
State television showed the coffins of the victims being carried across the streets of Damascus amid tight security, and the wailing of grieving women and men echoed across the district where the blast took place.
The opposition has accused the regime of President Bashar al-Assad of "staging" the bombing to win international sympathy.
"The area was closed shortly before the blast took place, and people in the area were warned to stay indoors," a Syrian activist based in Lebanon told dpa.
"Shortly after the blast, security forces were seen dropping personal belongings near the blown-up bus," he said on condition of anonymity for fear of reprisals.
Condemning the bombing, Arab League chief Nabil al-Arabi said Saturday in Cairo that he was extremely worried about the spiralling violence in Syria.
On Sunday, al-Arabi is to attend a meeting in Cairo of an Arab League committee to review the performance of an observer mission dispatched to Syria to end 10 months of bloodshed.
But Bassima Kadamani, the spokeswoman of the opposition Syrian National Council, was Saturday quoted by Arab media as saying: "The Arab League should admit that its observer mission has failed and should hand over the task to the United Nations."
A senior official in the regional bloc ruled out the possibility of recalling the observers any time soon.
"No Arab country has talked about the necessity of withdrawing the observers," the organization's assistant chief Adnan Eissa told reporters in Cairo.
Eissa said 153 Arab observers were already in Syria and would be joined by 10 more Jordanians later on Saturday.
Qatar's Prime Minister Hamad bin Jassim, who heads the Arab League committee on Syria, said Damascus was not implementing a deal aimed at stopping the violence.
"With deep regrets, the news is not good," bin Jassim told broadcaster Al Jazeera.
Meanwhile, Syrian security forces on Saturday killed nine people in the restive province of Homs, according to the opposition.
"The regime forces fired randomly at protesters in the rebellious neighbourhoods of Baba Amr and Khalidiyeh (in Homs)," opposition activist Omar Homsi told dpa.
More than 5,000 people have been killed in the government's crackdown on pro-democracy protesters since mid-Mach, according to the United Nations.