Syrian security forces have reportedly opened fire to stop tens of thousands of protesters holding rallies in front of visiting Arab League observers.

Activists say at least 35 people were killed in flashpoint cities like Hama, Deraa and Homs, all of whom were being visited by League monitors.

Running battles were fought at one of the largest rallies, in the Damascus suburb of Douma.

Security forces were accused of firing live rounds, nail bombs and tear gas.

Meanwhile, Syrian state media showed pictures of what it said were pro-government rallies in several cities, including Damascus, with protesters showing their anger at a foreign-orchestrated "plot" that is "targeting Syria's stability and security".

The UN says more than 5,000 people have been killed since the uprising against President Bashar al-Assad began in March. The government says 2,000 security forces personnel have died.