Seven people were killed in Homs' rebel-held neighborhood of al-Bayyada when they inhaled a poisonous gas sprayed by Syrian Army forces, opposition activists told Al-Jazeera early Monday.
According to the activists, scores of others suffered from side effects, including nausea, relaxed muscles, blurred vision, and breathing difficulties.
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Residents said they did not know the nature of the gas sprayed.
"The situation is very difficult. We do not have enough facemasks. We don't know what this gas is but medics are saying it's something similar to Sarin gas," Raji Rahmet Rabbou, an activist in Homs, told Al Jazeera.
In a video posted online a man who inhaled the gas said, "I felt something within a few seconds. I felt my throat block up as I tried to breathe. I couldn't see; I was blinded. I felt that my muscles were relaxed. I was paralyzed. People had to carry me here."
Meanwhile, the online edition of the German weekly Focus reported Sunday that elite soldiers from foreign armies are operating deep within Syrian territory in an effort to take control of the country's chemical arsenals.
According to the report, which is based on information from a NATO officer, soldiers from the IDF's Sayeret Matkal and elite French and American forces are working to prevent armed insurgent groups "with a strong presence of Islamic radicals" from seizing the dangerous substances in the event that the Syrian government collapses.
Russian Foreign Minister Sergei Lavrov said on Monday that Syrian authorities are unlikely to use chemical weapons as it would be a "political suicide" for them.
"I don’t believe Syria would use chemical weapons. It would be a political suicide for the government if it does," he said in an interview with the RT television network.
On Sunday opposition activists reported that dozens of people were killed and wounded in an air strike on a bakery in Syria's central Hama province, with some reporting up to 200 dead.
"There is no way to really know yet how many people were killed. When I got there, I could see piles of bodies all over the ground. There were women and children," said Samer al-Hamawi, an activist in the town of Halfaya, where the strike hit. "There are also dozens of wounded people."
Halfaya was seized by rebels last week as part of a campaign to push into new territories in the 21-month-old revolt against President Bashar Assad.