Germany, Denmark and Norway will supply Ukraine with 16 armoured howitzer artillery systems from next year, Berlin said Sunday, as Kyiv seeks heavier weapons to boost its fightback against Russia.

The announcement came after German Defence Minister Christine Lambrecht visited Ukraine this weekend for the first time since Moscow's invasion in February.

Germany, Denmark and Norway had agreed to jointly finance the procurement of the Slovakian Zuzana-2 guns at a cost of 92 million euros ($90.2 million), said the defence ministry in Berlin.

They will be produced in Slovakia, with delivery to Ukraine to begin in 2023, it said.

The new pledge still falls short of what Ukraine has been asking for. Kyiv has repeatedly sought Leopard battle tanks from Germany, but Chancellor Olaf Scholz's government has refused.

Scholz has said he does not want to go it alone on arms supplies and will only take decisions in consultation with his Western allies.

Speaking on public broadcaster ARD, Lambrecht again defended Berlin's weapons deliveries to Ukraine, insisting Germany was doing a lot to support Kyiv.

"We will continue to engage in a variety of ways and will again -- as we have up until now -- work together with partners," she told the "Bericht aus Berlin" show.

She also insisted that Germany would not become a direct party to the conflict.

"It is very clear -- for the German government as well as the whole of NATO: We will not become a party to the war," Lambrecht said.

Her visit Saturday to the southern port city of Odessa came a day after Russian President Vladimir Putin declared the annexation of four Ukrainian regions.

The annexations were unanimously condemned by Ukraine's allies, including Germany.

Lambrecht described how air raid sirens went off during her visit.

"We experienced that twice in a few hours, and had to move to a bunker. And for people there, that is reality," she told the ARD show. "That is everyday life."