The UN on Friday accused the Islamic State group and others in Syria of exploiting the COVID-19 pandemic to step up violence on civilians, describing the situation as a "ticking time-bomb".
United Nations rights chief Michelle Bachelet lamented a surge in violence in the country already ravaged by nearly a decade of conflict.
"We are receiving more reports every day of targeted killings and bombings from one end of the country to the other, with many such attacks taking place in populated areas," she said.
The rights chief highlighted that the surge in violence comes as the world is focused on halting the spread of the novel coronavirus, which has killed nearly 270,000 people worldwide.
"Various parties to the conflict in Syria... appear to view the global focus on the COVID-19 pandemic as an opportunity to regroup and inflict violence on the population," she said, voicing particular concern at an uptick in attacks claimed by IS jihadists.
"The deteriorating situation is a ticking time-bomb that must not be ignored."
The UN rights office said it had documented at least 35 civilian deaths in April due to attacks involving improvised explosive devices (IED), compared to seven a month earlier.
Since the start of March, it said there had been 33 IED attacks, including 26 in residential neighbourhoods, while seven other attacks hit markets.
- 'Give peace a chance' -
The rights office said that nearly all of the registered IED attacks had occurred in northern and eastern parts of the country under the control of Turkish armed forces and their allies, or the opposing Kurdish-led Syrian Democratic Forces (SDF).
It pointed in particular to a fuel-truck bomb that exploded on April 28 in a market in the northern Syrian city of Afrin, which it said killed 51 people, at least 29 of them civilians.
"Syria has been wracked by violence for nearly a decade resulting in the deaths of hundreds of thousands of people, and displacement of millions," Bachelet said, lamenting that "countless families have been traumatised, and numerous cities, towns, villages and individual homes have been destroyed."
"If the current patterns of violations and abuses continue to spread and escalate, there is a risk the country will enter another spiral of extreme and widespread violence committed with impunity by all parties to the conflict," she warned.
The Syrian conflict has killed more than 380,000 people since 2011 and has forced more than half of the country's pre-war population from their homes.
Bachelet backed UN Secretary-General Antonio Guterres's call for a global ceasefire amid the pandemic, and urged all sides in Syria's conflict to abide by the call.
"I urge all those continuing to fight, kill and displace the battered and beleaguered Syrian people to step back, and give peace a chance."