About 52 people were killed Sunday in separate operations launched by government troops in central and northern Syria, Xinhua quoted a human rights activist as saying.
Abdul-Karim al-Rihawi, head of the Syrian League for Human Rights, told Xinhua by phone that 42 people were killed in the northeastern province of Deir al-Zour and hundreds of others injured, as Syrian army troops in tanks stormed the province earlier Sunday.
At least 10 people were killed by government forces in the central town of Houleh in Homs province, al-Rihawi told Xinhua.
Meanwhile, the Local Coordination Committee said 70 people were killed during the military's operations in Deir al-Zour and other cities.
The death toll could not be independently verified as there was no official information of civilian casualties.
The Syrian authorities repeatedly said that there are armed men in Deir al-Zour and central cities of Homs and Hama, who are terrorizing people and sabotaging public and private properties.
The official SANA news agency said earlier in the day that army troops in Hama had exhumed mutilated bodies of 13 police personnel from the city's Orontes River.
Syrian President Bashar al-Assad stressed that his country is moving on steadily with the process of reforms and will simultaneously handle the outlaws to preserve the country's security.
Dealing with outlaws, who are cutting off roads, blocking the cities and terrorizing residents, "is the duty of the state to protect the life and security of its nationals," al-Assad was quoted by SANA as saying.
Meanwhile, a foreign ministry source expressed Sunday dismay over the statement issued a day earlier by the six-nation Gulf Cooperation Council calling for an immediate end to the violence and for a prompt implementation of reforms in Syria.
In a statement faxed to Xinhua, the foreign ministry said the GCC statement has "entirely disregarded facts presented by Syria, both in terms of slaughter and sabotage acts perpetrated by armed groups that target Syria's security and sovereignty, or in terms of the package of significant reforms announced by Syrian President Bashar Assad" in a speech he made on June 20.
Around 2,000 people are reported to have been killed in clashes in Syria since protesters took to the streets in mid-March demanding greater civil liberties. The violent crackdown by the authorities has received widespread condemnation from the UN, including the Security Council and top officials, as well as world leaders.
In response to the President's reference to the large number of lives lost among the security forces and police, UN chief Ban Ki-moon said he condemned the violence against both the civilians as well as security forces.
He also underscored that the use of force and mass arrests must stop immediately for the President's recently announced reform measures to have any credibility.
The Secretary-General reiterated his call on the Syrian Government to receive missions from the international humanitarian agencies and from the Office of the UN High Commissioner for Human Rights (OHCHR).
The protests in Syria are part of a wave of popular uprisings witnessed across North Africa and the Middle East since the start of this year that have already toppled regimes in Tunisia and Egypt, and led to ongoing conflict in Libya.