"We saw them with our own eyes. We call on the authorities to remove them immediately," said one Arab League observer. "We will contact the Arab League immediately and if they do not comply within 24 hours, there will be other measures."
Other demonstrators said troops opened fire on them to disperse a protest of 70,000 in Damascus, The Sun reported.
Despite the presence of observers, demonstrators said security forces killed at least 35 people Friday during the mass protests across the country.
The Local Co-ordination Committees, a network of anti-government groups inside Syria, said at least three people were killed Saturday by security forces.