"Dozens of tanks at dawn encircled the towns of Rastan and Talbisa, as well as the village of Deir Maaleh," a human rights activist told AFP in Nicosia by telephone.
The three centres are all situated between Homs and Hama in central Syria.

Tanks also blocked the highway linking Homs -- Syria's third-largest city and a flashpoint of pro-democracy protests -- to Hama, he said.
"There was intense gunfire by Syrian security forces at Rastan and Talbisa that wounded several people," the source said.

Security forces killed at least 12 protesters on Friday in dispersing demonstrations against the regime of Syrian President Bashar al-Assad, activists said.

More than 1,000 people have been killed and 10,000 others arrested since the revolt began, according to rights groups. Syrian authorities say 143 soldiers, security forces and police have been killed.

Foreign journalists are barred from travelling inside Syria, making it difficult to report on the unrest and verify witness accounts.

The government insists the unrest is the work of "armed terrorist gangs" backed by Islamists and foreign agitators.
It initially responded to the revolt by offering some concessions, including lifting the state of emergency in place for nearly five decades, but coupled this with a fierce crackdown.

The opposition has dismissed calls for dialogue, saying that could only take place once the violence ends, political prisoners are freed and reforms adopted.