Ukrainian President Petro Poroshenko has appealed to the US Congress to give his soldiers lethal military equipment for their fight against pro-Russian separatists, saying that one cannot win the war or keep the peace with blankets and night vision goggles.

During a visit to Washington DC on Thursday, the president told a joint meeting of the Senate and House of Representatives that his forces needed more political support throughout the world.

"They need more military equipment, both lethal and non-lethal, urgently," he said, asking for aid going beyond equipment such as night-vision goggles that Washington has already sent.

"Blankets, night-vision goggles are also important, but one cannot win the war with blankets," he said.

Poronshenko also called for more sanctions against Russia, whom Ukraine and NATO accuses of backing the rebels in the five-month conflict in eastern Ukraine that the UN says has killed more than 2,700 people.

He called Russia's annexation of Crimea one of the most "cynical acts of treachery in modern history".

The people of the United States stand with the people of Ukraine.

President Barack Obama

His emotional speech was interrupted frequently by applause and standing ovations.

"I also asked that the United States be forceful and reflect its principles with the respect of further sanctions against the aggressor," Poroshenko said.

The White House did announce a new $46m security package for Ukraine's military that includes counter-mortar radar to detect incoming artillery fire, but stopped short of the request for lethal aid.

The US will also provide vehicles and patrol boats, body armour and heavy engineering equipment, while also giving $7m to humanitarian organisations to assist people affected by the violence.

The US has so far provided about $60m in nonlethal aid to Ukraine's military.

"The people of the United States stand with the people of Ukraine," President Barack Obama declared as he sat side-by-side with Poroshenko in the Oval Office.

Endorsing Poroshenko's leadership, Obama said the Ukrainian president was "the right man" to lead his country through a difficult time.

Source: Agencies