Thousands of people have taken to the streets of Syria's flashpoint city of Homs to mourn several protesters reportedly killed by security forces on Friday, as opposition activists called for fresh strikes across the country. 

The funeral procession on Saturday was held a day after a government crackdown on nationwide demonstrations resulted in at least 11 deaths.

Most of those deaths occurred in Homs, Ammar Qurabi, the head of the National Organisation for Human Rights, an opposition group, said.

More than one million demonstrators called for an end to the Baathist party's 40-year rule across the country on Friday, which protest organisers dedicated to showing support for the military besieged city of Homs.

Since last Saturday, at least 50 people have been killed in Syria's third largest city as it braces against a heightened government crackdown, aimed at quelling mounting dissent, Syrian activists said.

According to residents, security forces, backed by tanks, have shelled many homes and buildings in numerous neighbourhoods and opened fire indiscriminately in the city in the last week.

'Defecting' troops

Meanwhile, state TV reported that 30 soldiers were injured during clashes with defected troops in Homs on Friday.

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Two explosions were heard overnight from inside the Syrian Army War College in Homs, two residents told the Reuters news agency, saying the sound of heavy gunfire was heard and ambulances were seen heading towards the compound.

"Smoke rose from inside the premises. The injured were taken to the military hospital. It looked like an operation of some sort," said one of the residents.

The fighting came amid reports that about 100 troops recently defected to the opposition in Homs.

Al Jazeera has not been able to independently verify reports of the violence due to restraints on foreign reporting in Syria.

Train derailed

Meanwhile, a passenger train derailed and caught fire in al-Souda, a town near Homs, on Saturday, killing the driver and injuring several people on board, after "saboteurs" tore out part of the tracks, state TV said.

The train, which was carrying around 480 passengers, was travelling from the northeastern city of Aleppo to the capital, Damascus.

State TV showed footage of several white-and-red carriages that had jumped the tracks and at least one overturned carriage.

Homs governor Ghassan Mustafa Abdul-Aal called it a "terrorist and criminal'' act and said it was a "clear message'' to everyone who says that the protest movement calling for the ouster of President Bashar Assad is peaceful.

Abdul-Aal did not elaborate on or mention any evidence indicating who was behind the incident.

Separately, two special advisers to UN chief Ban Ki-moon warned that there was a "serious possibility'' that the Syrian government had committed crimes against humanity.

In a statement, Francis Deng, the adviser on preventing genocide, and Edward Luck, the adviser of the responsibility to protect civilians in conflict, pointed on Friday to "persistent reports of widespread and systematic human rights violations by Syrian security forces responding to anti-government protests across the country.''

Thousands of people have been killed and at least 12,000 arrested during the Syrian government's crackdown on the five-month uprising.

Source: Al Jazeera and agencies