Activists say at least 20 civilians have been killed by security forces across Syria, 11 of them in the flashpoint region of Hama.
The London-based Syrian Observatory for Human Rights said in a statement that troops backed by tanks stormed the city of Hama after a three-day general strike.
It was the first armored incursion into Hama since a tank offensive in August ended large protests in the city center.
Opposition fighters tried to stop the advancing forces at a bridge in the city, and two armored vehicles were reported destroyed.
The UN says at least 5,000 people have been killed in Syria since the beginning of the nine-month pro-democracy uprising against the rule of President Bashar al-Assad.
compiled from agency reports