Kyiv has signed several 10-year security agreements with NATO countries that outline long-term Western support for Ukraine in the face of a Russian invasion now in its third year.

"Our teams -- Ukraine and the United States -- have started working on a bilateral security agreement," Zelensky said in his evening address on social media, adding that it could be a "truly exemplary" deal.

The agreements signed so far -- including with Britain, France and Germany -- are not mutual defence pacts, but have symbolic importance as a show of committment by the West to support Kyiv militarily, politically and financially for years to come.

Zelensky held a telephone call with US President Joe Biden earlier on Monday after the US Congress advanced a long-stalled package of military aid for Kyiv over the weekend.

The Ukrainian leader said after the call that "all the dots have been dotted in the agreements on ATACMS (Army Tactical Missile Systems) for Ukraine."

The longer-range missiles, which have a maximum range of around 300 kilometres (190 miles) -- depending on the ammunition supplied -- were first delivered to Ukraine last year in what both sides said would be a boost to Kyiv's battlefield capabilities.

The versions previously supplied to Kyiv had a range capped at 165 kilometres, amid concerns over supplying powerful weapons to Ukraine that would have been able to hit deeper into Russian territory.