BEIRUT — Syrian authorities closed off entire areas in several tense cities on Friday, setting up checkpoints and roadblocks ahead of planned anti-government protests after prayers at the country’s mosques, activists said.

President Bashar Assad has gone to extreme measures to try to crush the protest movement that has engulfed several provinces across the country. Authorities have sent tanks and snipers to major flashpoint cities and arrested thousands of people in the past two weeks.

More than 775 people have been killed and thousands detained since the uprising against Assad’s repressive regime began in mid-March, according to human rights groups.

On Thursday, Syrian forces surrounded the city of Hama, the scene of a brutal attack ordered by Assad’s father in 1982, when thousands of people were killed.

The impoverished southern city of Daraa, where the protests first erupted, remains under siege. The coastal city of Banias and central city of Homs were also surrounded by tanks and activists said security forces were carrying out house-to-house searches and arrests in an effort to punish or intimidate any would be protesters.

Despite the military operations and arrest raids meant to pre-empt the rallies, activists called for more protests Friday. The Syrian Revolution 2011 Facebook page, which is run by activists, called for protests in solidarity with Syrian women who have been detained or killed by security forces.

“We will come out for the dignity of our (women) detainees, together toward freedom,” it said.

Assad, 45, is determined to crush the popular rebellion despite international pressure and sanctions from Europe and the United States. His government has led one of the most brutal crackdowns in the wave of popular revolts sweeping the Arab world.

On Thursday, U.S. Secretary of State Hillary Rodham Clinton slammed the government’s assault on demonstrators and said the violence indicates that Assad is weak, though she stopped short of saying he must quit.

“Treating one’s own people in this way is in fact a sign of remarkable weakness,” Clinton said during a trip to Greenland.

The revolt was touched off in mid-March by the arrest of teenagers who scrawled anti-regime graffiti on a wall. Since then, the protests have spread nationwide and the death toll already has exceeded those seen during the uprisings in Yemen and Tunisia.

The government’s bloody crackdown has increased in intensity in recent days. The army shelled residential areas in central and southern Syria on Wednesday, killing 19 people, a human rights group said.