At least eight people were killed as Damascus its biggest day of anti-regime protests when Syrians turned out en masse to dismiss reforms offered by President Bashar al-Assad as too little and too late.

Teargas and live bullets were fired at demonstrators leaving Friday prayers in several areas of the capital and elsewhere, but Syrian state TV blamed unidentified gunmen for some deaths.

Activists reported a total of 12 people killed, including three civilians and a policeman in Barzeh, in north Damascus, and four in the south.

There were also protests in the central city of Homs and, more unusually, in Aleppo, Syria's second city, which has been largely peaceful so far.

State media also reported a large shipment of weapons had been seized in Latakia, allegedly destined for "armed groups" in northern Syria.

The government announced it was calling off its military operation in the villages around Jisr al-Shughour and the Turkish border – possibly in response to mounting pressure from Ankara.

Turkey's foreign minister, Ahmet Davutoglu, said he had conveyed Turkey's "concerns and thoughts" about the operation to his Syrian counterpart. The US and Britain had both warned of the risk of escalation if Syria did not halt its deployment.

The scale and geographical spread of the latest protests – dubbed "the Friday of the end of legitimacy" – appeared to underline Assad's failure to dampen opposition fervour. In an address on Monday he spoke of dialogue and reform, but democracy activists dismissed his offers as cosmetic or insufficient.

Opposition leaders in Damascus were reported to be planning a public meeting next week to discuss future strategy.

It was the 15th Friday on which Syrians have taken to the streets, and many are looking for the trigger for what they see as the inevitable downfall of the regime — either the economy collapsing or heavier outside pressure led by Turkey. Opposition figures and independent analysts see Ramadan – which starts on 1 August – as the deadline, as daily mosque attendance will make mass protests more likely.

In a belated attempt to regain the initiative and win some credibility, the regime has allowed a number of foreign journalists to enter Damascus, although they are escorted by official minders and unable to move freely. The government says 500 members of the security forces have died since protests erupted in mid-March. Activists say more than 1,400 civilians have been killed and about 10,000 detained.

Nidaa Hassan is the pseudonym of a journalist in Damascus