BEIRUT (Reuters) - Syrian army and allied forces supported by Russian warplanes made further advances as they pressed an offensive against insurgents on Monday, in the fiercest clashes for nearly a week, a monitor said.

Russian jets carried out at least 30 air strikes on the town of Kafr Nabuda in Hama province in western Syria, and hundreds of shells hit the area as the Syrian army and Hezbollah fighters seized part of it, the Syrian Observatory for Human Rights said.

Forces loyal to President Bashar al-Assad have in the past few days recaptured territory close to the government's coastal heartland in the west thanks to Russia's intervention, reversing rebel advances made earlier this year.

Moscow says its air campaign targets Islamic State, but most of the strikes have hit rival insurgent groups fighting against Assad, some of which are supported by the United States.

Pro-government forces including the Lebanese group Hezbollah on Monday captured the southern part of Kafr Nabuda, the Observatory's Rami Abdulrahman said.

The fighting, shelling and air strikes killed and wounded dozens of insurgents, he said.

"These are the most violent battles in the northern countryside (of Hama) since the start of joint operations several days ago" between the Russian air force and Syrian ground forces, he said.

Lebanese-based television station al-Mayadeen also reported the takeover of the southern part of Kafr Nabuda.

Kafr Nabuda's capture would bring government forces closer to insurgent-held positions along the main highway that links Syria's main cities. "The town is very important and strategic," Abdulrahman said.

The Syrian army and Hezbollah on Sunday took control of Tal Skik on the other side of the highway in southern Idlib province. Many of Russia's air strikes have hit the surrounding area, which also lies east of Assad's stronghold Latakia.

Russia began its air campaign on September 30, alarming a U.S.-led coalition which is carrying out its own air strikes against Islamic State in Syria and Iraq.

(Reporting by John Davison; Editing by Dominic Evans)