That raises the number of internally displaced persons to 6.2,000,000, while about 5.6 are refugees in neighboring countries, according to United Nations figures.
Moumtzis said most of the newly displaced had been forced on the move by escalations in fighting in the former rebel bastion of Eastern Ghouta and within the northwestern province of Idlib, which is nearly entirely controlled by various jihadist and hardline rebels.
Moumtzis cited reports of a deadly air strike on Sunday that had killed 11 people and hit a pediatric hospital.
Moumtzis called on the guarantors of the detente zones in the Arab country, Russia, Turkey and Iran to intensify their commitment to maintaining the ceasefire in effect, especially in the northwestern province of Idlib, where "2.5,000,000 civilians are increasingly moving towards the Turkish border", their last means of escape, he said.
More than 350,000 people have been killed in the Syrian war since it started in 2011 with the brutal repression of anti-government protests. "Our worry is that with the Idlib situation we may have not (yet) seen the worst in Syria".
Schaap said CARE and its partners inside Syria have seen it firsthand this year, when tens of thousands of civilians had to leave their homes in eastern Ghouta and northern parts of Homs province "to find refuge in overcrowded shelters". "There is no other location to move them to [in Syria]", he told a news briefing in Geneva.
At the same time, the mishmash of armed groups in the province are increasingly fighting amongst themselves.
"A special solution needs to be found for all these groups inside Idlib because the current composition makes it highly explosive".
Five other civilians were killed in other raids nearby.
But he said far too few aid convoys were making it through to such areas, with only nine succeeding since January.
"According to available information, there was fierce fighting in the past twenty-four hours in the said district of the province of Idlib between a large formation of the Jabhat al-Nusra terrorist organization [outlawed in Russia] and the Jaysh al-Ahrar irreconcilable opposition grouping with the use of heavy artillery guns", the defense ministry said.
An aid convoy reached Douma in the enclave of eastern Ghouta outside Damascus on Sunday, but the government did not allow United Nations aid workers to accompany it, he said, saying that direct access was vital.