The United Nations on Tuesday sharply criticized both the Ukrainian government and the pro-Russian rebels for turning bus stops, schools, markets and hospitals into battlegrounds where civilians are getting killed.

Indiscriminate shelling and an escalation in the fighting in eastern Ukraine have killed at least 224 civilians in the past three weeks alone, the U.N. said, raising the overall death toll to 5,358 people since April.

Hostilities between Russian-backed separatists and Ukrainian troops resumed with a vengeance in January after a month of relative calm. The latest peace talks broke down Saturday, with both sides blaming the other for prolonging the fighting.

"Bus stops and public transport, marketplaces, schools and kindergartens, hospitals and residential areas have become battlegrounds ... in clear breach of international humanitarian law," U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein said, adding that 545 civilians were wounded in the last three weeks as well.

He blamed the high civilian death toll on "the indiscriminate shelling of residential areas in both government-controlled territory and in areas controlled by the armed groups."

Rebels in the separatist stronghold of Donetsk said Tuesday that artillery fire killed at least eight people and wounded 22 others in the past day, while Ukrainian military spokesman Andriy Lysenko said five servicemen had been killed and 27 wounded in the same period.

The rebels' main offensive is now directed at Debaltseve, a railway junction between the rebel-held cities of Luhansk and Donetsk. Separatists say they are not planning to storm Debaltseve itself because of the potential for civilian casualties.

Ukraine accuses Russia of arming the rebels, a charge that Russia denies. But Western military experts say the sheer amount of heavy weapons in rebel hands belies that denial.

President Barack Obama has so far opposed sending lethal assistance to aid Ukraine's government, but a senior administration official told The Associated Press the surge in fighting has spurred the White House to review that policy.

But German Chancellor Angela Merkel reiterated Tuesday in Berlin that Germany would not deliver lethal weapons to Ukraine, saying she intends to focus on finding a "diplomatic solution" to the conflict.

Ukrainian Prime Minister Arseniy Yatsenyuk, meanwhile, signed a decree abolishing national ID travel between Ukraine and Russia, saying Ukraine needed to tighten its controls along the border.