Syria imposed on Tuesday a total ban on all demonstrations after warning of a crackdown on an “armed revolt” by Islamist radicals and security forces fired on protesters in the city of Homs, killing at least four.

Interior Minister Mohammed Ibrahim al-Shaar told people “to refrain from taking part in all marches, demonstrations or sit-ins under any banner whatsoever”, state news agency SANA reported.

He warned that if demonstrations were held, “the laws in force in Syria will be applied in the interest of the safety of the people and the stability of the country”.

Mr. Shaar was understood to be alluding to the emergency law in place since 1963. Its repeal has been a central demand of reformists demonstrating since March 15, and President Bashar al-Assad promised at the weekend to rescind it within a week.

The law restricts civil liberties, imposes restrictions on public gatherings, freedom of movement and allows the “arrest of anyone suspected of posing a threat to security”.

When the protests first began, the authorities relaxed its enforcement to permit peaceful gatherings, but Mr. Shaar's announcement would appear to close that loophole.

The announcement came hours after the authorities vowed to suppress what they called an “armed revolt” in the country by Salafists, Muslims who espouse an austere form of Sunni Islam that seeks a return to practices common in the early days of the faith.

The authorities said three Army officers and three children were killed by “armed criminal gangs” around the city of Homs, authorities announced.

An activist said “the sit-in was dispersed with force. There was heavy gunfire.” He said that very early on Tuesday the security forces swarmed into Al-Saa Square, where some 20,000 people were staging a sit-in, scattering protesters who had vowed not to leave until Mr. Assad stepped down. Another said four people were killed, but gave no details.

At least 200 people have been killed by security forces or plain-clothes police since the start of the protest movement, according to Amnesty International.

Just hours before the attack on Al-Saa Square, the government vowed to suppress “armed revolt” it said was undermining national security. It accused such groups of killing soldiers, policemen and civilians, and of attacking public and private property, and warned that “their terrorist activities will not be tolerated”.

The demonstrators arrived in their thousands at Al-Saa Square on Monday, many setting up tents, a day after 11 people were killed by security forces in Homs and a nearby town during a day of massive nationwide protests.

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