WASHINGTON (REUTERS) - Nato's European members need to increase their defence spending in light of Russia's action in Ukraine, US Defence Secretary Chuck Hagel said in planned remarks released on Friday.

"We must see renewed financial commitments from all Nato members," Mr Hagel said in excerpts from a speech on the Nato alliance to be delivered at the Wilson Centre and released by the Pentagon.

His comments come amid increased violence between Ukraine loyalists and Russian separatists despite an international peace deal, and echoed calls by other top US officials this week for Nato members to shore up their commitments.

The level of defence spending by Nato allies has been a longstanding concern of US defence secretaries. Only a handful of the 28 countries actually spend 2 per cent of their GDP on defence as agreed under the Nato partnership.

On Tuesday, US Secretary of State John Kerry also urged Nato allies not meeting the 2 per cent benchmark to boost their payments to the alliance in the next five years.

Russia's recent incursion in Ukraine has rekindled concerns among Nato allies. On Friday, pro-Russian rebels shot down two Ukrainian helicopters, killing two people, as Ukrainian forces tightened their siege of separatist-held Slaviansk.

"Russia's actions in Ukraine have made Nato's value abundantly clear," Mr Hagel said in his prepared remarks. "Over the long term, we should expect Russia to test our alliance's purpose, stamina, and commitment," he said.

Mr Hagel called for Nato members' financial ministers or budget officials to attend an alliance meeting to discuss defence spending, saying members must "break through the fiscal impasse."

Still, US officials have been seeking a financial boost for Nato for years. Three years ago, then-Defence Secretary Robert Gates used his final speech in Europe as Pentagon chief to deliver a parting shot at the allies, saying Nato risked "collective military irrelevance" unless they bore more of the burden and boosted military spending.