European Council President Donald Tusk is calling on Russia to use its influence with separatists in eastern Ukraine to end an upsurge of fighting that has caused many casualties and aggravated the humanitarian situation.

"We are reminded again of the continued challenge posed by Russia's aggression in eastern Ukraine," Tusk said on February 2. "The fighting must stop immediately. The cease-fire must be honored."

Ukraine says two of its servicemen were killed and 10 others wounded in the country's east in the previous 24 hours as heavy fighting between government forces and Russia-backed separatists entered its fifth day.

Ukrainian officials had earlier reported the deaths of eight soldiers in the past few days, the highest toll in weeks, and casualties among civilians and separatist fighters were also reported.

Kyiv's police chief in the Donetsk province, Vyacheslav Abroskin, said one woman was killed and three men wounded in a shelling attack.

The separatists said one of their fighters was killed and another was wounded in the past 24 hours.

The sides traded blame for the surge in hostilities that are concentrated around the government-controlled city of Avdiyivka, where shelling left many residents without electricity, water supplies, and heating in temperatures well below freezing.

By February 2, the water supply and heating in the town north of the separatist-held provincial capital of Donetsk had been partially restored, the Associated Press reported.

The news agency said sounds of shelling were heard in Avdiyivka in the early afternoon, adding that fighting appeared to be less intense than in previous days.

Army officers have set up seven camps for civilians and were distributing gruel and tea in makeshift street kitchens, AFP reported.

A deal signed in Minsk in February 2015 called for a cease-fire and steps to end the conflict that has killed more than 9,750 people in eastern Ukraine since April 2014.

Meeting in the Belarusian capital on February 1, the Trilateral Contact Group (TCG), which is attempting to regulate the conflict, urged both sides to adhere scrupulously to the Minsk agreements and to withdraw heavy weaponry away from the contact line as previously agreed.

The TCG, which includes Ukraine, Russia, and the Organization for Security and Cooperation in Europe (OSCE), also called for "safe and secure access" for OSCE monitors and the "facilitation of humanitarian efforts" aimed at restoring water and electricity supplies.

NATO Secretary-General Jens Stoltenberg called the renewed fighting "the most serious spike in violence in a long time," adding that the humanitarian situation for civilians in Avdiyivka is "dire, with 20,000 people facing freezing temperatures without heat, electricity, and water."

Stoltenberg also called on Russia "to use its considerable influence over the separatists to bring the violence to an end."

The UN Security Council on January 31 expressed "grave concern" over the "dangerous deterioration" in eastern Ukraine and called for a halt to the violence.

Kyiv and Moscow are accusing each other of being responsible for the latest flare-up of hostilities in eastern Ukraine, with the Kremlin saying the escalation shows the need for a resumption in dialogue between the United States and Russia.

Russian-U.S. relations are badly strained over Moscow's aggression in Ukraine, its actions in Syria, and what U.S. intelligence agencies say was state-directed interference in the U.S. presidential election.

U.S. President Donald Trump has called for improved relations with Russia, and both the White House and the Kremlin said a conversation between Trump and Russian President Vladimir Putin on January 28 was a positive sign.

Despite substantial evidence, Russia denies claims by Kyiv, NATO, and Western governments that it stirred up separatism in the region and has sent troops and weapons to Ukraine to support the separatists.

The European Union, United States, and other states have imposed sanctions on Russia over the conflict, as well as for its annexation of Ukraine’s Crimean Peninsula in March 2014.

Earlier this week in Berlin, Ukrainian President Petro Poroshenko told German Chancellor Angela Merkel that the West should extend and strengthen sanctions against Russia if there is no progress in implementing the Minsk agreements on resolving the conflict.

In an interview published on February 2, Poroshenko said Russia was paying "a high price for its aggression" thanks to the sanctions.

"The standard of living has fallen considerably, the Russian currency is losing its value," he told the Berliner Morgenpost newspaper. "It is the sanctions that will keep Putin at the negotiating table and will force him to fully implement the Minsk peace agreement."

The president also said he does not expect military aid from Europe.

"We have our own army and we can fight for our independence on our own," Poroshenko said. "If you ask me, what kind of support I need most from the European Union, I have a simple answer: unity."

With reporting by AP, Reuters, and UNIAN