According to reports, the refinery was working only at 10 percent of its capacity when it came under attack.
The Homs refinery had a capacity of 5.7 million tons per year before the crisis began in the country.
The other main plant, located in Banias near the Mediterranean coast, is still working at 80 percent of its capacity.
Syria’s oil industry has been massively hit since the unrest began in the country in 2011. According to reports, the Western powers and their regional allies — especially Qatar, Saudi Arabia, and Turkey — are supporting the militants operating inside Syria.
The United Nations said on Monday that more than four million more Syrians will be forced out of their homes in 2014 by the escalating conflict in the country.
Two million Syrians are expected to take refuge outside the country while another 2.25 million others are predicted to be internally displaced in the next year.