Berlin sent three Patriot units to eastern Poland in January after a deadly blast struck a Polish village in late 2022, believed to be from a stray Ukrainian air defence missile.

The deployment of the advanced US-made systems was originally meant to be for a maximum of six months, as Berlin seeks to ensure its own weapons stocks are not depleted.

But the defence ministry said in a statement that it had offered to allow Poland to keep the systems "over the summer, probably until the end of the year".

The ministry added however that there were no plans to extend the deployment beyond 2023. From 2024, the systems would make an "important contribution" to a NATO rapid response force, the ministry said.

In addition, recent deployments of the Patriot systems -- not only in Poland, but also in Slovakia and Lithuania -- meant measures were needed to renew personnel and material, it said.

Poland's defence minister initially pushed back at Germany's offer to deploy Patriot units, instead calling on Berlin to send them to Ukraine to combat the Russian invasion, though he later agreed.

Germany, a major contributor of weapons to Kyiv, later sent a Patriot system to Ukraine as well.