Published: Feb 08, 2012 8:53 PM EST

BEIRUT (AP) - European officials said Wednesday they plan harsher economic sanctions on Syria, including a possible flight ban, as ally Russia pursued its own rival effort to resolve the crisis by trying to broker talks between the regime and opposition.
    
Amid the diplomacy, President Bashar Assad's regime pushed ahead with a relentless offensive on the city of Homs, the epicenter of the 11-month-old uprising. Troops with mortars and heavy machine guns blasted at least four restive neighborhoods in the city, killing at least 53 people, activists said. The assault has reportedly left hundreds dead the past five days.
    
Amnesty International warned Homs was "turning into a major humanitarian crisis." It urged Russia to use its influence to stop the Syrian military from using heavy weapons in residential areas.
    
In online video taken by activists, the screech of rockets and the blasts of impacts can be heard, raising a cloud of smoke and dust from an apartment tower in Homs' Baba Amr district. Fires blaze from a house and from the city's refinery hit in the fighting, and buildings across the urban landscape have gaping holes and crumbling walls from days of shelling.
    
Russia and the West had an acrimonious falling out over how to deal with Syria's crisis after Moscow and Beijing over the weekend blocked a Western-Arab attempt to bring U.N. pressure on President Bashar Assad to step down.
    
Now each camp is pushing ahead on rival tracks. Russia has taken a line close to Assad's position, saying reforms and dialogue can bring an end to the fighting, while avoiding calls for his departure. Western and Arab nations have moved to isolate Assad while considering forming a coalition of nations to provide help to the opposition. The U.S. says it is just a matter of time before Assad goes.
    
Turkey, a former ally of Assad that fell out with him over the bloodshed, is proposing an international conference in Istanbul or elsewhere in the Mideast to discuss creating an "international platform that would represent the conscience of humanity" to help Syrians, Foreign Minister Ahmet Davutoglu told a press conference.
    
He dismissed Assad's promises to Russia that he would carry out reforms, saying he had made and broken similar promises to Turkey.
    
"We cannot allow the bloodshed of more of our brothers with these tactics to buy time," Davutoglu told NTV television earlier.
    
The U.N.'s top human rights official, Navi Pillay, called for immediate action to stop the bloodshed, saying she was "appalled" by the regime's offensive in Homs. The killings show an "extreme urgency for the international community to cut through the politics and take effective action to protect the Syrian population," she said.
    
Pillay's office estimated in early January that 5,400 people have been killed in Syria's upheaval since the uprising and the crackdown against it began in March. But it says it has been unable to update the estimate because of chaos on the ground. Hundreds have been reported killed since.
    
In Brussels, a senior European Union official said foreign ministers from the 27-nation bloc will decide on harsher sanctions against Syria aimed at weakening Assad when they meet on Feb. 27. The EU has already halted oil purchases from Syria, among other sanctions.
    
The official said the new measures may include bans on the import of Syrian phosphates, on commercial flights between Syria and Europe, and on financial transactions with the country's central bank. The European Union takes 40 percent of Syria's phosphate exports. The official spoke on condition of anonymity in keeping with EU rules.
    
The U.S. closed its embassy in Damascus on Monday and five European countries and six Arab Gulf nations have pulled their ambassadors out of Damascus over the past two days. Germany, whose envoy left Syria this month, said he would not be replaced.
    
Russia, in contrast, has urged Assad to hold dialogue with the opposition and move ahead with reforms he has promised, including a new constitution, permission to form political parties and eventual parliamentary elections.
    
All those provisions are nonstarters with the opposition, which dismisses promises of reform as empty gestures, refuses negotiations while violence continues and says Assad's removal is the only option.
    
Russian Prime Minister Vladimir Putin said Wednesday that outside forces should let Syrians settle their conflict "independently."
    
"We should not act like a bull in a china shop," Putin said, according to the ITAR-TASS news agency. "We have to give people a chance to make decisions about their destiny independently, to help, to give advice, to put limits somewhere so that the opposing sides would not have a chance to use arms, but not to interfere."
    
Russian Foreign Minister Sergey Lavrov, who met with Assad Tuesday in Damascus, told reporters in Moscow that the Syrian president delegated to his vice president, Farouk al-Sharaa, responsibility for holding a dialogue with the opposition.
    
The Assad regime says terrorists acting out a foreign conspiracy to destabilize the country are behind the uprising, not people seeking to transform the authoritarian regime. It has vowed to continue the crackdown to uproot them even while starting reforms.
    
In Homs, the Britain-based Syrian Observatory for Human Rights said at least 53 people were killed in Wednesday's shelling of the neighborhoods of Bayadah, Baba Amr, Khaldiyeh and Karm el-Zeytoun.
    
The death toll, which the group says it gathers from contacts on the ground, could not be independently confirmed. Syrian authorities keep tight control on the media.
    
Omar Shaker, an activist in Baba Amr, said his neighborhood was under "very intense shelling" by tanks, mortars, artillery and heavy machine guns.
    
"The situation is dire. We are short of food, water and medical aid. Doctors have collapsed after treating the wounded without rest for five days," Shaker said. "We want Lavrov to come and spend a night in Homs to see what we have been passing through."
    
The head of the Observatory, Rami Abdul-Rahman, said the regime was trying "exhaust rebels in preparation for storming neighborhoods."
    
The Observatory reported at least another 13 civilians killed around the country.
    
Syrian state TV blamed gunmen firing mortars for the fire at Homs' oil refinery, one of two in Syria, where two fuel tankers were ablaze. Activists in online videos blamed regime shelling.
    
State TV said "terrorists" also denoted a car bomb in the Homs neighborhood of Bayadah, killing and wounding a number of civilians and troops.
    
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Associated Press writers Mansur Mirovalev in Moscow, Slobodan Lekic and Selcan Hacaoglu in Brussels contributed to this report.

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