The protest in Jisr al-Shaghour drew thousands of people on June 4, an activist said. Syrian forces opened fire on protesters, the activist and the Syrian Observatory for Human Rights said.

The group, which is regularly in touch with activists in different parts of the country, said 25 people were confirmed dead following the Saturday incident.

Syrian state-run news agency SANA, meanwhile, said four policemen were killed and more than 20 other people were wounded by "armed terrorist groups" that attacked buildings in the city.

The groups were seen using "various types of weapons," the report said. "The terrorist groups spread fear in the hearts of citizens who called upon the competent authorities to interfere forcefully to protect them and bring back security and stability."

Throughout the Syrian uprising, the government has described protesters as "terrorists" and "armed criminals."

The number of people killed in the government's crackdown on demonstrators has exceeded 1,000, according to the United Nations.