Hundreds of thousands demonstrate as security forces kill at least 11 people with president rumoured to call elections

Hundreds of thousands of Syrians turned out for anti-regime demonstrations across the country on Friday with at least 11 people reported killed by security forces and tensions mounting in the runup to the Ramadan holiday.

Casualty figures – collated by two Syrian human rights groups – were down on previous weeks but the numbers of demonstrators appeared to be some of the largest yet seen in the four-month uprising.

In Aleppo, Syria's second city, unarmed military cadets were seen marching with civilian protesters and calling for the overthrow of the regime and the departure of President Bashar al-Assad.

Damascus was unusually quiet after large demonstrations closer to the city centre last week but protests were reported from Deir Ezzor in the east to Suweida in the south. All were called to express solidarity with the people of the central city of Homs – the focal point of recent unrest – where some 40 people have been killed in the last few days amid worries of rising sectarian tensions. Five of the latest casualties were killed there.

Amateur video footage posted on the internet showed many thousands gathering after prayers on a day dubbed "Friday of the descendants of Khalid", a reference to a disciple of the prophet Muhammad who unified the Arabian Peninsula in the seventh century and is buried in Homs.

Nearby Hama, scene of a notorious 1982 massacre during the rule of Assad's father Hafez, saw hundreds of thousands in central Assi Square. But there was no visible security presence in the city.

Large protests were also reported for the first time from Aleppo, where one of Friday's fatalities was killed. Syrian TV reported that a civilian had been killed by an "armed gang" – the regime's habitual term for almost all protests.

In Damascus there were signs of a more restrained approach, with security forces firing into the air or using tear gas to prevent trouble spreading.

Activists reported checkpoints and a heavy security presence in Rukn ad-Deen, a largely Kurdish neighbourhood in the north-east of the city and the far eastern area of Qaboun where a mass funeral was held on Thursday. But protests went ahead as usual in Midan, a conservative district close to the old walled city.

Live streaming and better-quality pictures have been emerging from Syria this week despite the government's attempts to curb social media and temporarily block access to email services and Twitter.

In Midan a video clip showed protesters clapping and shouting: "The people are free, Syria is free." Footage from Aleppo showed a man drenched in blood being carried away. And in largely Kurdish Qamishli on the border with Turkey, teargas was fired to break up a protest.

Expressions of solidarity with Homs – pinned down by troops and tanks on the streets – came at the end of a week when at least 40 people were killed there, some of them reportedly in sectarian clashes.

But reports of sectarian strife have been hotly contested by activists and some analysts. "The protest movement does appear to be predominantly peaceful and non-sectarian but as state control weakens … people with other grievances may be taking advantage," said a western diplomat in Damascus.

That may be the case in Homs' northern neighbourhoods where Alawites and Sunnis are segregated into adjacent neighbourhoods.

Reports of revenge killings and violence on the part of "Shabiha" thugs allied with the government are multiplying. Some sources said state media reports of the targeting of a military bus near Rastan, north of Homs, on Thursday, killing two, may have been a case of a revenge attack.

In Homs activists and residents reported a rise in defections, including eight military intelligence personnel who changed sides after a brutal crackdown.

Activists said that several tank crews this week defected and joined protesters in the eastern town of Albu Kamal bordering Iraq's tribal Sunni heartland.

Footage from Aleppo showing unarmed army cadets marching with civilians was a striking novelty but it was difficult to judge its scale or wider significance.

Syrian activists are warning protesters who imitate slogans from Egypt and Tunisia (where the army changed sides and helped overthrow both presidents) such as "the people and the army are one hand!" that they should not count on the military changing sides. "This is a very different situation here and we know that," said one Damascus activist.

Delegations from Brazil, India and Turkey were reported to be in the capital to meet Assad amid reports that he will soon deliver his fourth speech since the uprising began. It is understood he will offer to abrogate article eight of the Syrian constitution, which provides for a leading role for the ruling Ba'ath party.

Assad is also rumoured to be considering calling presidential elections – overseen by delegations from abroad – several months after a new political parties law is put into effect.

"This could be the only peaceful way out of the situation," said one analyst. "But I am not sure the street will accept it at this stage."

In other developments, protesters destroyed a statue of Hafez al-Assad in Hasaka, prompting security forces to open fire, al-Arabiya TV reported. Hundreds more marched in the southern town of Suweida while demonstrations took place in the north-western province of Idlib.

According to the Syrian Observatory for Human Rights, 1,419 civilians and 352 members of the security forces have been killed since 15 March, while more than 1,300 people have been arrested.

Nour Ali is a pseudonym for a journalist in Damascus