Reports say the offensive is targeting several Sunni Muslim neighborhoods that have risen up against the 11-year rule of President Bashar al-Assad -- a member of the minority Alawite community in Syria that has dominated the Sunni-majority country for the last five decades.
The London-based Syrian Observatory for Human Rights says at least 47 people were killed overnight by tank and artillery barrages as well as heavy machine-gun fire from Syrian Army troops.
Independent confirmation of the reports was not available because of Syrian government restrictions on foreign journalists.
Activists in the city of Homs say the overnight shelling targeted four neighborhoods at the hub of antiregime protests since March -- Bayadah, Bab Amr, Khaldiyeh, and Karm al-Zeytun.
A spokesman for the opposition Local Coordination Committees says government troops at dawn began storming Khalidiyeh, Bab Amr, and the neighborhood of Inshaat -- seizing a hospital and arresting injured people there.
Spokesman Omar Idibi also said the advance by government troops was preventing injured civilians from reaching the hospital for treatment.
According to Western media reports, the overnight death toll in Homs includes 18 prematurely born babies who died at a hospital because their incubators shut down as a result of electricity cuts. This could not be independently confirmed.
Lavrov Urges Talks
The assault comes a day after Assad promised visiting Russian Foreign Minister Sergei Lavrov he would try to end the violence.
Lavrov on February 8 declined to say whether Moscow thinks Assad should step down, saying only that the Syrian crisis should be resolved by "agreement among Syrians themselves and should be acceptable to all Syrians."
Lavrov maintained that the Syrian president is prepared for dialogue and urged opposition forces to open talks with the regime. Lavrov added that the results of such a dialogue should not be "predetermined" by the international community.
He also encouraged those who might have influence with the Syrian opposition to agree to talks with the government.
"This readiness [of the Syrian leadership] is an important factor which must be taken into consideration, and we hope that all those who have any influence on the opposition -- on the various opposition groups -- will encourage them to start such a dialogue," he said.
Lavrov criticized a decision by the six-country Gulf Cooperation Council to recall ambassadors from Syria, saying it would not create conditions favorable to implementing an Arab League initiative for halting the violence in Syria. The Arab League plan calls for a cease-fire and for Assad to hand over power to a deputy.
Earlier this week, Moscow offered to host talks between the Syrian government and opposition forces. That offer was accepted by Damascus but rejected by the opposition, which views Moscow as an ally of Assad.
In another development, the Turkish government has announced plans for an international conference on Syria "as soon as possible." Turkish Foreign Minister Ahmet Davutoglu said the conference will include regional states and world powers.
Davutoglu also said he is traveling to Washington to discuss Syria with U.S. officials, and that Turkish Prime Minister Recep Tayyip Erdogan planned to discuss Syria with Russian President Dmitry Medvedev by telephone.
Compiled from agency reports