Prime Minister Viktor Orbán said on Tuesday that Ukraine's accession to NATO would immediately result in war with Russia, which would carry the risk of a third world war, so Ukraine must not be allowed to join either NATO or the European Union.

The prime minister said on Facebook that Hungary has a primary security interest in not belonging to the same integration framework as Ukraine.

He said the signatories of a recently launched initiative of Hungarian citizens open to political thinking included people that he used to fight together with for Hungarians' freedom and the country's independence 35 years ago.

"For obvious reasons, the respect resulting from this has since worn thin; but the shared past still obliges. This is why I publish the following response," he said.

PM Orbán said the signatories neglected Hungary's interests, and their assessment of the consequences of the continuation of the Russia-Ukraine war was flawed.

"They are also wrong in identifying the European Union's interests. If the EU accepts Ukraine as a member, it will currently result in an open war, and following a ceasefire it would result in the continual risk of a Europe-Russia war," he said.

"If we want to help Ukraine ... then instead of a war that destroys the country and results in the dispersion of the Ukrainian people, or utopistic promises of integration, we should offer them a form of cooperation that will bring an end to the war, offer efficient help, and does not sacrifice the interests of Hungary and the EU on the altar of an ill-fated and delirious strategy," he said.

"Ceterum censeo, Hungary comes first," he added.