The Latest on the conflict in Syria as government troops, backed by Russian air power, continue to encircle rebel-held districts of the northern city of Aleppo (all times local):

6:15 p.m.

Syrian opposition activists say Turkish troops are firing artillery shells at areas in northern Syria that are held by Syrian Kurdish fighters.

The Britain-based Syrian Observatory for Human Rights said the artillery strikes are targeting the village of Malkiyeh and the Mannagh air base, which was captured by Kurdish fighters and their allies earlier this week.

Amer Hassan, an opposition activist based in the northern Syrian town of Azaz, confirmed that Turkish troops have shelled the Mannagh air base.

A Turkish Foreign Ministry spokesman told The Associated Press that he had no information on the cross-border shelling.

Turkish troops have bombarded areas under the control of Syria's main Kurdish military, the People's Protection Units or YPG, multiple times in the past.

Turkey says the YPG is affiliated with the Kurdish PKK movement, which has waged a long and bloody insurgency in southeast Turkey.

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2:30 p.m.

Syrian state TV and an opposition activist group say government forces have captured another village near Aleppo, tightening the noose around rebel-held parts of the northern city.

State TV and the Britain-based Syrian Observatory for Human Rights say troops captured Tamoura on Saturday.

Hezbollah-run Al-Manar TV says troops are now overlooking the town of Hayan and parts of the town of Anadan. The Lebanese militant group is fighting alongside forces loyal to Syrian President Bashar Assad.

Syrian troops have been advancing under cover of intense Russian airstrikes with the aim of besieging rebel-held parts of Aleppo, Syria's largest city.

The United States and Russia have announced a plan to halt the violence within a week, but it's unclear whether fighters on the ground will adhere to it.