The US wants to work with Russia to end the separatist conflict in eastern Ukraine, President Donald Trump has said.

In a telephone call with Ukrainian President Petro Poroshenko on 4 February, Trump said he would work with "Ukraine, Russia and all other parties involved to help them restore peace along the border," according to a White House readout of the conversation.

Poroshenko's office told Reuters that the leaders discussed "settlement of the situation in the Donbass and achieving peace via political and diplomatic means".

"The two sides discussed strengthening the strategic partnership between Ukraine and the United States," it said.

The phone conversation took place following intense fighting between Ukrainian troops and Russian-backed rebel forces in eastern Ukraine that reportedly left at least 35 people dead.

On 4 February, Oleg Anashchenko, a senior rebel commander, was killed in a car bomb attack in Luhansk.

The conflict in Ukraine began with Russia's annexation of Crimea in March 2014.

The US imposed sanctions on Moscow in response to its actions in eastern Ukraine, but the election victory of Trump – an open admirer of Russian President Vladimir Putin – had raised concerns that Washington's Ukraine policy might shift.

In an interview with Fox News over the weekend, Trump insisted that his "respect" for Putin would not influence his foreign policy decisions.

"I do respect him, but I respect a lot of people," he said. "That doesn't mean I'm going to get along with him."

The president added that he would rather get along with the Russian leader than otherwise and that he would appreciate any help from Moscow in the fight against Islamic State (Isis) in Syria and Iraq.

"But, [Putin] is a killer," Fox News host Bill O'Reilly said.

"There are a lot of killers," Trump replied. "We've got a lot of killers. What do you think? Our country's so innocent?"