Lithuania has supplied 150 tonnes of ammunition to Ukrainian troops fighting pro-Russian separatists in the country's east, the Baltic NATO member said Saturday.

Defence Minister Juozas Olekas said it was Lithuania's duty to help a "devoted friend who was attacked by Russia".

"We responded to the Ukrainian request and hope it will make their life easier," the minister told AFP Saturday.

Olekas said it was the second time Vilnius has sent military aid to Ukraine since it began fighting pro-Russian separatists after Moscow's 2014 annexation of the Crimean peninsula.

Most other NATO countries have so far held off arming Ukraine to avoid angering Russia, which has warned that lethal military aid could escalate the conflict.

Lithuania, a eurozone member of three million, has also provided medical care for over 100 Ukrainian troops injured in clashes with pro-Russia rebels, and formed a joint brigade with Kiev and Warsaw.

Kiev and the West say that Russia is arming separatists who control parts of eastern Ukraine and is sending troops to fight alongside them.

Moscow has repeatedly denied this and accuses Kiev of acting in bad faith.

The warring sides have put in place a fresh ceasefire since Thursday aimed at halting a recent spike in fighting in time for the start of the new school year.

The conflict has claimed some 9,600 lives since early 2014, with more than two million people displaced.