Ukraine's SBU security agency says it has uncovered a spy network being run by the Hungarian state to obtain intelligence about Ukraine's defences.

Asked about the announcement, Hungarian Foreign Minister Peter Szijjarto said he regarded it as Ukrainian "propaganda" that should be treated with caution.

The SBU said it had detained two suspected agents who, it said, were being run by Hungarian military intelligence.

It said it was the first time in the history of Ukraine that a Hungarian spy network had been found to be working against Kyiv's interests.

There was no immediate response to a request for comment from the Hungarian government.

Hungary is part of the European Union and NATO, two blocs with which Ukraine is closely allied in the war it is fighting with Russia.

However, relations between the two countries have often been fraught. Hungarian Prime Minister Viktor Orban has been sceptical about Western military aid for Ukraine.

He has also maintained relations with Vladimir Putin, putting him at odds with most other EU leaders, who have sought to isolate the Russian president since Moscow's 2022 invasion of Ukraine.

The SBU said the two suspects are former members of the Ukrainian military, adding they are in custody, and have been given notice they are under suspicion of committing state treason.

It said they were recruited by a handler in Hungarian military intelligence, and given cash and special equipment for secret communication.

The SBU added the agents were tasked with passing on to their handler details about Ukraine's air defence batteries, and other military capabilities in the Transcarpathia region of southern Ukraine, which borders Hungary.

Ukraine is home to around 150,000 ethnic Hungarians, most of them in the Transcarpathia region. Kyiv and Orban's government have clashed in the past over the rights of this community to use their native language.

Szijjarto accused Ukraine of often using anti-Hungarian propaganda that proved unfounded.

"Therefore, I would ask everyone to exercise caution with regard to all such reports appearing in Ukrainian propaganda," he said.

"If we receive any details or official information, then we will be able to deal with this. Until then, I must classify this as propaganda that must be handled with caution."