The Syrian conflict has killed more than 136,000 people  since it began in March 2011, with January of this year being one of the bloodiest months on record, a leading Syrian NGO said Saturday.
The Syrian Observatory for Human Rights, a watchdog based in Britain, said that at least 136,227 people had died according to the latest death toll.
Among those killed are 47,998 civilians, including more than 7,300 children, the group said, according to Agence France Presse (AFP) news agency.
"January was among the bloodiest months since the beginning of the conflict," Observatory director Rami Abdel Rahman said, AFP reported.
"We in the Syrian Observatory for Human Rights will continue to call on all actors on the international stage to do their humanitarian and moral duty to press for the Syrian file to be referred to the International Criminal Court," the group said in a statement, according to AFP.
The NGO added that it is seeking to put the “murderers of the Syrian people and those who have collaborated with them”  on trial for their crimes.
The Observatory last conducted a toll at the end of the December, when the number of dead stood at 130,433, according to AFP. However, fierce clashes between rebels and the regime and infighting between different rebel factions  have claimed nearly 6,000 lives in the past month alone.
The NGO reported that at least 31,629 opposition fighters, including more than 8,000 jihadists, had been killed since the start of the conflict in March 2011.
Within the regime’s ranks, 53,167 soldiers and militiamen were killed, along with 271 members of Lebanese Shiite organization Hezbollah  and 338 members of other foreign Shiite groups fighting on behalf of the government.
The Observatory’s toll also includes 2,824 unidentified individuals, according to AFP.
The group warned that the real toll could be much higher than what is recorded, as "extreme secrecy" by rebels, jihadists and regime troops has been affecting the toll’s accuracy. 
Syria’s now all-out sectarian conflict began in March 2011 with peaceful anti-government demonstrations, which were cracked down on hard by the regime of President Bashar al-Assad. Since the onset of the crisis, both sides of the conflict have been accused of war crimes.