(CNN) -- The restive Syrian city of Homs was in a state of mourning on Wednesday, as citizens flocked to funerals for people slain in the streets the day before, an activist told CNN.
But security forces didn't assault mourners as they had on Tuesday, the activist said.
Tension and violence between security forces and demonstrators have plagued the western Syrian city for days.
Activists told CNN that a funeral procession Tuesday for slain protesters was attacked by security. The Local Coordination Committees of Syria said at least 16 people were killed and 33 were wounded on Tuesday.
On Wednesday, the activist said, security forces made arrests and raids after the funeral processions ended. Videos surfacing on the Internet showed mourners marching in the streets.
CNN could not independently verify the information.
Also Wednesday, Human Rights Watch said Syrian security forces have intensified their campaign of mass arrests in cities that have had anti-government protests.
The cities include Hama, Homs, and suburbs around Damascus, the group said.
Citing "reliable activists and witnesses," it estimated that security forces have arrested more than 2,000 anti-government protesters, medical professionals caring for wounded protesters and people alleged to have given information to international news media and human rights organizations.
"President Assad talks reform but continues to practice repression, not only through the widespread killings of demonstrators but also through mass arrests," said Sarah Leah Whitson, Middle East director at Human Rights Watch.
The Local Coordination Committees, an affiliation of groups that organizes and reports on protests in Syria, estimates that more than 15,000 people arrested since the beginning of the protests remain in detention, HRW said.
"Human Rights Watch has already documented widespread torture from the accounts of people who have been released, causing concern that many detainees still in detention are being tortured," the group said.
Independent accounts of the situation in Syria are hard to come by; most of the international media have been barred from the country.
The unrest in Syria began in mid-March after teens were arrested for writing anti-government graffiti in the southern city of Daraa, according to Amnesty International.
As the clashes intensified, demonstrators changed their demands, from calls for freedom and an end to abuses by the security forces to calls for the regime's overthrow.
U.N. Secretary-General Ban Ki-moon on Wednesday called for "Syrian authorities to stop repression immediately" and said "all sides should refrain from using violence." He said mass arrests should be halted and President Bashar al-Assad should respond to citizens' grievances.
He repeated the need "for a credible and inclusive dialogue, which should be carried out without delay and be part of a broad and genuine reform effort."