Syrian security forces have killed eight people as thousands of anti-government protesters taunted President Bashar al-Assad.

Witnesses and rights groups say several hundred people converged on the main square in the central city of Homs Monday after a U.N. humanitarian team visited the town. Pro-government troops fired on the protesters, many of whom had shouted “Gadhafi is gone; now it is your turn, Bashar!” At least six people were killed.

Similar demonstrations were held in other Syrian cities, including Hama, where two more civilians were reported killed.

Earlier, the U.N. high commissioner for human rights, Navi Pillay, said the Syrian government has resorted to an apparent “shoot-to-kill” policy against civilians. She told the U.N. Human Rights Council that more than 2,200 people have been killed in the unrest. The U.N. special rapporteur on torture also briefed the council Monday, saying the “threshold of systematic and widespread violence has clearly been reached.”

All four Arab nations on the U.N. body – Jordan, Kuwait, Qatar and Saudi Arabia – joined calls condemning the violence and urged Syria to cooperate with an international investigation on whether crimes against humanity have been committed in the country. The U.N. team in Homs had been granted permission to visit some of the protest centers to assess the humanitarian situation in those locations.

Also Monday, U.N. Secretary-General Ban Ki-moon said it is “troubling” that Mr. Assad has not kept his word about ending the brutal military crackdown in his country.

Mr. Ban told reporters in New York that the Syrian president assured him in a recent phone conversation that military operations had stopped.

The Syrian leader has defended his crackdown by describing the opposition as armed gangs and terrorists. He also said criticism from Western countries means nothing to him.

Mr. Assad said during a lengthy interview with Syria's state-run television Sunday that his security forces are making gains against the five-month-old uprising. He said he is “not worried” about the uprising, and he warned of consequences for any military action against his country.

The United States, the European Union and other Western powers have said that Mr. Assad must step down.

The Syrian leader repeated plans to introduce reforms, adding that he expects new elections for Syria's national assembly in six months. He said that laws on the establishment of new political parties will be ready in the next few days, and that people who want to create a new party will have a 45-day period to apply through a committee.