The International Committee of the Red Cross said Friday it is "deplorable" people are getting used to the fact so many civilians are being killed each day in Syria's war.
The ICRC said that humanitarian aid efforts, though continuing, were falling short of what was required to take care of millions of people affected by the devastating two-year-old conflict.
"It is deplorable that high numbers of civilian casualties are now a daily occurrence to which people are unfortunately getting accustomed," said Robert Mardini, who heads the Red Cross' regional operations.
"These ongoing violations of international humanitarian law and of basic humanitarian principles by all sides must stop," he said in a statement.
Civilians were the most affected by the war, which the United Nations says has killed more than 70,000 people, forced over 1.1 million to flee abroad and some four million to be displaced.
"Hundreds are dying daily in Syria. Millions have been displaced inside the country while others have fled to neighbouring countries to live in harsh conditions," said Mardini.
"Health standards have fallen dramatically, medical facilities have been targeted and health workers killed, intimidated or detained while trying to save lives."
Mardini's remarks come a day after Amnesty International said the UN Security Council must refer war crimes committed by both sides in the conflict to the International Criminal Court.
"How many more civilians must die before the UN Security Council refers the situation to the prosecutor of the International Criminal Court so that there can be accountability for these horrendous crimes?" asked Ann Harrison, Amnesty's deputy director for the Middle East and North Africa.
The rights watchdog has repeatedly accused both President Bashar al-Assad's regime and rebel fighters of atrocities.
Mardini also said tens of thousands of Syrians were missing or detained.
"Despite repeated attempts to resume our visits to detainees, very little has been achieved so far. Today, we have no first-hand information on the situation of detainees and this is very worrying for us," Mardini said.
Mardini said aid efforts were short of what were required even as ICRC with the Syrian Arab Red Crescent worked across front lines to deliver aid to some of the worst hit opposition and government-controlled areas.
"Over the last two years millions have received aid, but it is not enough. Needs are growing at a faster pace than our ability to respond. Security constraints and lack of access to some areas prevent us responding as we should do," he said.