Western allies are exploring long-term military backing for Ukraine that could encompass support for non-NATO member Moldova as well, British Foreign Secretary Liz Truss said in an interview published Saturday.

Moscow "absolutely" poses a threat to Moldova as President Vladimir Putin seeks to restore a "greater Russia", she told the Daily Telegraph newspaper.

"How do we ensure that there is deterrence by denial, that Ukraine is permanently able to defend itself and how do we guarantee that happens? That's what we are working on at the moment," Truss said.

"And that also applies to other vulnerable states such as Moldova.

"Because again, the threat is broader from Russia, we also need to make sure that they are equipped to NATO standards."

A month ago, a series of blasts hit Moldova's Russian-backed separatist region of Transnistria, raising fears of spillover from the war in neighbouring Ukraine.

On May 4, European Council president Charles Michel pledged to increase EU military aid to Moldova, which applied to join the bloc in March.