|The central Syrian city of Homs has endured nearly two weeks of bombardment by government forces [AFP]
Syrian opposition activists say at least 22 people have been killed in continued military assault on opposition strongholds, while a prominent blogger and other leading activists have been arrested, just hours before a UN vote on the crisis.
President Bashar al-Assad's forces attacked the central city of Homs for a twelfth straight day on Thursday, with 18 people killed in central Hama province and four others dying in the southern city of Deraa, activists reported.
Al Jazeera's Rula Amin, reporting from Beirut in neighbouring Lebanon, said: "Syrian government forces seem to be on the offensive, pushing back into areas where the [opposition] Free Syrian Army (FSA) had taken control in the past few weeks.
"They have been conducting severe seizures and bombardments in many areas in the country: Hama, Homs and suburbs of Damascus, and this morning in Deraa in the south."
There was no comment from Syrian authorities, who tightly restrict media access to the country.
The assault comes a day after Assad promised that a referendum on the new draft constitution will be held later this month. The opposition, however, has said that it rejects any political moves while attacks continue against protesters.
The arrest of the blogger, Razan Ghazzawi, a symbol of the uprising against Assad's rule, and a prominent human-rights activist, Mazen Darwish, along with his wife and 11 others, was reported by the human-rights lawyer Anwar Bunni.
Bunni said Ghazzawi was arrested on Thursday in an early afternoon raid on the Syrian Centre for Media and Freedom of Expression, which is located in central Damascus and is headed by Darwish.
"We at the Syrian Centre for Legal Studies condemn these arrests and call on Syrian authorities to immediately release them," Bunni said in a statement.
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The Paris-based watchdog, Reporters Without Borders, condemned the arrests and demanded the activists' immediate release.
The escalation in violence comes as a source told the Interfax news agency that Russia will not support a UN General Assembly draft resolution calling on Assad to stop the deadly crackdown on civilians.
"In its current form the draft is of an unbalanced character and does not take account of our position," the "informed source" told the agency in the run-up to a vote, expected later on Thursday, on the draft.
For his part, Ban Ki-moon, the UN general-secretary, said crimes against humanity had probably been committed by Syrian forces, echoing concerns of Navi Pillay, the UN's human rights chief, who has called for the situation in Syria to be referred to the International Criminal Court.
"We see neighbourhoods shelled indiscriminately, hospitals used as torture centres, children as young as 10 years old killed and abused. We see almost a certain crimes against humanity," Ban said during a visit to Austria on Thursday.
The resolution at the General Assembly has been proposed by Arab states including Qatar, Egypt and Saudi Arabia, as well as Western powers which have expressed support for protesters in Syria, including the US, the UK and France.
It calls for the General Assembly to express grave concern at the deterioration of the situation in Syria, and to back an Arab League peace initiative which calls for "a Syrian-led political transition to a democratic political system".
Opposition activist re-elected
In other developments on Thursday, the Syrian National Council (SNC) re-elected Burhan Ghalioun as president of the bloc. His mandate as leader of the coalition, which has become the main voice of the Syrian opposition, runs to April 15.
"The SNC renews its pledge to fulfil the demands of the Syrian people and its responsibilities towards them, and to ensure that none of the bloodshed has been in vain," the SNC executive committee said in a statement after meeting in Doha, Qatar.
In-depth coverage of escalating violence across Syria
"The SNC’s president will have a dedicated professional team to facilitate communications between the SNC’s committees, bureaus, activists on the ground, relief workers, and support for the Free Syrian Army."
Syrian security forces continued their campaign even as Assad on Wednesday set February 26 as the date for a referendum on a new constitution, which the government says will lead to multi-party elections within 90 days.
But it was rejected by the opposition and the West, with the US calling it "laughable".
China, which drew global condemnation when it joined Russia in vetoing a Security Council resolution on Syria, said on Thursday it would send an envoy to Damascus to push for a "peaceful" end to the conflict.
Zhai Jun, the Chinese deputy foreign minister, will visit Syria from February 17 to 18, a foreign ministry spokesman said.
Russia and China have so far refused to yield to diplomatic pressure over Syria.
However, France said on Thursday that compromise with Russia at the Security Council was possible to end the violence in Syria in the short term, and that France was ready to work on a new resolution to provide humanitarian aid to Syrians.