Security forces raided homes across Syria, arresting regime opponents, as more funerals were planned Sunday for people killed in a bloody crackdown on protests, activists said.

Students meanwhile called for action and two MPs resigned after at least 13 mourners were shot dead Saturday when Syrians swarmed the streets to bury scores of demonstrators killed in massive protests the previous day.

Human Rights Watch urged the United Nations to probe the "carnage" from the "Good Friday" demonstrations, when scores of protesters were killed as tens of thousands took to the streets of cities and towns across the country.

The New York-based watchdog called for US and EU "sanctions on Syrian officials who bear responsibility for the use of lethal force against peaceful protesters and the arbitrary detention and torture of hundreds of protesters, and push for similar sanctions to be imposed by the Security Council."

The Syrian Observatory for Human Rights said dozens of people were arrested in northern Syria on Friday, just a day after President Bashar Al-Assad had lifted decades of emergency rule.

The London-based group gave the names of 18 men who were rounded up in the northern cities of Idlib, Raqqa and Aleppo, but said "dozens more were arrested in other Syrian towns." Syrian authorities "continue to carry out arbitrary arrests despite the lifting of emergency rule," it said in a statement, calling for the release of political prisoners and an independent probe of Friday's killings.

Meanwhile, Daniel Saud, head of the Committees for the Defence of Democracy, Freedoms and Human Rights in Syria, was arrested at his home in the northwestern city of Banias, lawyer Khalil Maatouk told AFP.

On Thursday, Assad signed decrees ending a draconian state of emergency imposed by the ruling Baath Party when it seized power in 1963, restricting freedom of assembly, to placate more than a month of "freedom" protests.

He also abolished the state security court that has tried scores of regime opponents over the years outside the normal judicial system and whose verdicts cannot be appealed.

Tens of thousands swarmed cities and towns across Syria on Friday to test the implementation of the reforms, but scores were killed when security forces fired live rounds and tear gas at the crowds, activists said.

Rights activists have said the death toll from Friday's protests could top 100.

"After Friday’s carnage, it is no longer enough to condemn the violence," Joe Stork, deputy Middle East director at Human Rights Watch, said in a statement. "Faced with the Syrian authorities’ 'shoot to kill' strategy, the international community needs to impose sanctions on those ordering the shooting of protesters," he said.

On Saturday at least 13 mourners who took part in the funeral processions of some of those killed on Friday were shot dead. Thousands of mourners prepared to bury on Sunday four of them who were killed in the southern town of Noa, near the protest hub of Daraa, and protests were expected after the funeral, an activist told AFP.

"Dozens of vehicles are cruising the streets of Daraa and will be picking up mourners who want to join the funeral in Noa," which has been decked by banners ahead of the planned protest, the activist said.

The banners echoed a raft of demands by the protesters who want across-the-board political reforms as well as the dissolution of the feared security services who have cracked down mercilessly against demonstrators.

The Syrian Revolution 2011 group, a driving force behind the protests, indicated its determination to keep up the pressure on Assad's regime. "We are going out (on the streets) today, tomorrow and the day after," said a statement posted Sunday on its Facebook page.

Meanwhile public figures, including independent Daraa lawmakers Nasser Al-Hariri and Khalil Al-Rifai, have resigned in frustration at the crackdown.

Daraa's top religious leader, Mufti Rizq Abdulrahman Abazeid, also quit, as well as a member of the Daraa city council, Bassam Al-Zamel who told Al-Jazeera television "it is a duty on us to present our resignation." "I call on the president to contain the security forces," responsible for weeks of a deadly crackdown against protesters, Zamel said.

Students in Daraa and Damascus declared a general strike in all Syrian universities until "massacring the peaceful protesters comes to a stop and all prisoners of conscience and opinions are released," a statement said. They also demanded all of the people's "legal and justified demands" for freedom and democracy are met, not just promised, and "justice" for everyone responsible for the killings.

More than 300 people have been killed in Syria since protests were launched 15 March, according to a compilation of figures provided by Amnesty International and Syrian activists. Syria has blamed "armed gangs" for the unrest and said it was aimed at fuelling sectarian strife among the country's multi-religious and multi-ethnic communities.

The crackdown unleashed a chorus of international condemnation. US President Barack Obama blasted Syria's use of violence and accused Assad's regime of seeking Iran's aid in the brutal crackdown -- a charge denied by Tehran and Damascus.

EU foreign policy chief Catherine Ashton echoed world leaders calling the crackdown "intolerable," and even Syria ally Russia urged Damascus to speed up reform.