Ukraine is on an “irreversible” path to Nato membership, US secretary of state Antony Blinken has said, advancing assurances that the country will be allowed to join the Western military alliance but only after its war with Russia ends.

A joint communique from all 32 Nato allies meeting in Washington is expected later on Wednesday to cement that “irreversible” Nato commitment to Ukraine, a European official said, speaking on condition of anonymity to discuss it before its release.

Ukraine President Volodymyr Zelensky has battled for at least a firm guarantee from Nato that Ukraine can join the military alliance.

Ukrainian President Volodymyr Zelensky is in Washington with Nato leaders (Jose Luis Magana/AP)

The US and some other countries have opposed membership for Ukraine while the conflict with Russia continues to avoid allies being drawn into a larger war.

They also have stressed that Ukraine must make significant steps to address corruption as well as other systemic reforms.

Russian President Vladimir Putin has long bitterly opposed neighbuoring Ukraine’s fight to join the Western alliance, declaring it an encroachment on Russia’s security and interests.

Nato secretary-general Jens Stoltenberg underlined that Ukraine will not join the alliance’s ranks immediately.

“To invite a new ally, we need consensus. All allies agree that Ukraine will become a member but it’s too early to say when that will happen,” he told reporters.