The Russian foreign ministry has expressed “deep concern” at reports from anonymous sources that Saudi Arabia is planning to supply Syrian rebels with anti-tank and anti-aircraft missile launchers to “turn the tide” in the three-year conflict.

“There is a chance that if these powerful weapons get into the hands of the terrorists who have flooded the country, they are likely to turn up far beyond the borders of Syria itself,” said a statement from the ministry.

The second report this month that these weapons will be given to rebels was published by AFP news agency over the weekend, and was indirectly confirmed up by several recent developments.

The Western-backed Syrian opposition chief Ahmad Jarba promised that “powerful arms will be arriving soon” to rebel units during a visit last week to rebel fighters on the ground. Meanwhile, his principal backers hosted Pakistan's army Chief of Staff, General Raheel Sharif in Riyadh earlier this month. Pakistan makes versions of both types of weapons, and has been earmarked as the supplier by Saudi officials, according to the source.

Riyadh has long insisted that rebels should be armed with these fearsome portable launchers, which are key to fighting a Syrian army that has air superiority and far more armored vehicles. But US and other Western allies have repeatedly refused the rebels’ requests, reasonably fearing that even one or two such weapons could be used for a major terrorist attack against a civilian aircraft.

According to the report, Jordan will be providing facilities to store the weapons before the delivery to Syria. Jordan’s territory is also being used by “by specialists from the Central Intelligence Agency” to train Syrian fighters, according to the Syrian National Coalition’s representative in the US, Najib Al-Ghadban, cited by Asharq Al-Awsat. Jordanian officials however denied this report .

These developments trigger concerns that the militants are preparing to open a new “southern” battlefield in the coming months, the Russian ministry warned.

A renewed hunger for a military resolution, following the virtual breakdown of the Geneva peace talks will test its resolve.

“The Syrian conflict cannot be solved by force, and we ask all those considering the military option to reconsider, and allow the Syrians to reach a peaceful agreement within the parameters of Geneva, and without outside interference,” said the Russian statement.

The long-awaited talks in the Alpine city last month have produced localized peace treaties to alleviate humanitarian suffering, but gave no hint of a political reconciliation between the warring sides.

However, on 22 February the United Nations Security Council unanimously adopted a resolution to boost humanitarian aid access in Syria to ease civilian suffering. It strongly condemned the “widespread violations of human rights and international humanitarian law by the Syrian authorities, as well as the human rights abuses and violations of international humanitarian law by armed groups.”

The war-torn country has witnessed 140,000 people killed over the last three years while a major part of the population has fled their homes and are in urgent need of humanitarian assistance.

The resolution calls on all parties in the Syrian conflict to allow “rapid, safe and unhindered humanitarian access for UN humanitarian agencies and their implementing partners” to ensure that humanitarian assistance “reaches people in need through the most direct routes.”