Defense Minister Oleksiy Reznikov tweeted that four more HIMARS rocket launchers from Washington and the first in a batch of German MARS-II systems had arrived in Ukraine.

He thanked his German counterpart Christine Lambrecht, saying "our artillerymen salute our German partners!"

In response to Washington's latest deliveries, Reznikov wrote that he was "grateful" to President Joe Biden and his US counterpart Lloyd Austin for "strengthening" the Ukrainian army.

"We have proven to be smart operators of this weapon. The sound of the #HIMARS volley has become a top hit of this summer at the front lines!" Reznikov wrote.

Reznikov last month asked Washington to send more of the systems, saying Kyiv's forces had used them to destroy around 30 Russian command stations and ammunition depots.

He said that at least 100 of these systems were needed for an effective counter-offensive against Moscow's troops.

So far the United States has agreed to send some 20 HIMARS systems to Ukraine under a major program to equip Kyiv's forces.

He also renewed a call for longer-range ammunition to cut off Russian units from their support.

Washington has hailed as "excellent" the use of HIMARS by the Ukrainian army, highlighting their impact on the battlefield.

But Biden's administration has so far refused to send longer-range ammunition, fearing that Ukraine would strike targets inside Russian territory and potentially expand the war into a direct clash with the West.

The German-provided MLRS MARS II is the third variety of sophisticated rocket-launcher system -- after HIMARS and MLRS M270 -- to be given to Ukraine to help it battle Russia's invasion.

He also renewed a call for longer-range ammunition to cut off Russian units from their support.