Extremist groups in the Syrian province of Aleppo received reinforcements from Turkey, Russia’s Foreign Ministry has said.
The Islamist groups Al-Nusra Front and Ahrar ash-Sham groups “got serious reinforcements from Turkey,” ahead of the planned peace talks, Foreign Ministry spokeswoman Maria Zakharova said. Al-Nusra Front is al-Qaida's Syrian affiliate.
"Unfortunately, in recent days, it’s especially noticeable that ahead of the planned start of the inter-Syrian negotiations in Geneva the activities of terrorist groups have intensified.
"Obviously, they’re trying to turn the tide in their favor on the battlefield,” Foreign Ministry spokeswoman Maria Zakharova said in Moscow.
Zakharova said that Russia is also concerned over Turkey's increased incursions into Syria.
"It cannot be ruled out that… fortifications [built by Turkey] along the Syrian-Turkish border may be used by militant groups as strongholds.
"While all parties involved pin their hopes on the start of a meaningful and… inclusive dialogue between the Syrian government and the opposition, external forces continue to help militants in Syria, including terrorist groups, providing them with arms and ammunition," she said.
Zakharova said that Moscow was “surprised” by recent comments from the United States, that they don’t see Russia's efforts in regard to providing humanitarian aid to Syria.
"This is very strange, especially since the State Department allegedly sees everything, including Russian tanks that are being flown in or crawling into the territory of other states, but there’s no humanitarian aid in sight," she said.
Zakharova said that Russia’s Emergencies Ministry has performed 30 flights “not only to Syria, but also to Lebanon and Jordan” in January, delivering 600 tons of food and essentials to those affected by war.
“Russia has also been involved in evacuation of citizens who want to leave dangerous areas," she added.
The spokeswoman said that the Syrian government has now sent an official appeal to UN secretary-general and chairman of the UN Security Council over the “repeated incursions of Turkish troops into Syrian border areas.”
Talks aimed at ending the Syrian conflict are set to take place on Monday. The first UN-brokered meeting in the Swiss city will be "proximity talks" in which representatives of the government and opposition will gather separately.
Meanwhile, on Sunday, the Nusra Front group seized two prominent media activists, shutting down their radio station and burning rebel flags in the process.
The opposition radio station, Radio Fresh, said on its social media pages that Raed Fares and Hadi Abdullah were abducted by Nusra in an early morning raid in the town of Kafranbel.
The Syrian Observatory for Human Rights, a UK-based group that tracks the country's civil war, says Mr Fares, who runs the station, was taken because he had criticised the group.
In January 2014, Islamic State militants sprayed his car with 40 bullets, putting him in hospital for three months, and in December of that year, Nusra detained and beat him for three days.
The nearly five-year-old war has claimed more than 250,000 lives, displaced millions and given an opening to Isis to seize land.
United States' Secretary of State John Kerry and its UN ambassador, Samantha Power have been pushing for more assistance to be given to the Syrian rebels.
Hundreds of protesters have gathered outside the office of an opposition newspaper in Istanbul after two journalists were jailed pending trial for reporting on alleged Turkish arms smuggling to Syria.
The US is demanding that Turkey close a 60-mile stretch of its border with Syria which is the sole remaining crossing point for Isis militants, including some of those involved in the massacre in Paris and other terrorist plots.