The opposition Syrian National Coalition rejected Thursday an oil and gas exploration deal Damascus signed the day before with a Russian company, linking it to arms deals.
"The Coalition condemns the signing of this deal, which aims to swap the riches of our homeland for Russian weapons destined to kill the Syrian people," a statement said.
The deal permits the exploration of an area of 2,190 square kilometres (850 square miles) in the Mediterranean.
It was signed on Wednesday by Syrian Oil Minister Suleiman Abbas, Syria's General Petroleum Co and the Russian Soyuzneftegaz company.
"The Russian firm agreeing one of the most important contracts in the region with the criminal regime while fighting rages unabated is proof that the Russian government has signed a deal to send more arms to kill Syrians," it said.
"The Russian government is an accomplice in the spilling of Syrian blood through its support for the Assad regime, the main source of international terrorism," the statement added.
Abbas said during Wednesday's signing ceremony that the contract covers "25 years, over several phases," adding that "the cost of exploration and discovery is $100 million (73 million euros)".
General Petroleum Co head Ali Abbas told AFP: "It will be financed by Russia, and should oil and gas be discovered in commercial quantities, Moscow will recover the exploration costs."
Hard-hit by international sanctions, Syria's oil production has plummeted by 90 percent since the start of the uprising against President Bashar al-Assad in March 2011.