Hungary's foreign minister, Peter Szijjarto, accused Ukraine's leadership on Wednesday of seeking to intervene in the upcoming Hungarian election, an allegation later denied by his Ukrainian counterpart in an incident that strained relations between the two countries further.

Szijjarto alleged in a social media video that there was "ongoing cooperation between the Hungarian left and representatives of the Ukrainian administration," and that Ukraine was attempting to influence Hungary's April 3 election in favor of an opposition coalition.

The remarks come after Ukrainian President Volodymyr Zelensky made several recent remarks critical of the Hungarian government's handling of the war.

Hungary has refused to supply Ukraine with weapons or allow their movement across its borders, while also opposing levying sanctions against Russian energy imports, arguing that doing so would deeply damage its economy.

Read more: Hungary not to supply arms to Ukraine

This policy prompted Zelensky to issue a direct request on Friday to Hungarian Prime Minister Viktor Orban, widely regarded as the Kremlin's closest partner in the European Union, to take a firmer stance on the war and "defend his country."

“I want to stop here and be honest, once and for all. You have to decide for yourself who you are with,” Zelenskyy said, addressing Orban, in a video call with EU leaders.

Szijjarto alleged on Wednesday that Ukraine's foreign minister, Dmytro Kuleba, had phoned the Ukrainian embassy in Budapest to discuss ways to sway Hungary's election.

He said that opposition parties hoping to defeat Orban had vowed to equip Ukraine with weapons and to cut off imports of Russian gas and oil if elected.

But speaking to the Evropeiska Pravda newspaper on Wednesday, Kuleba denied the charges.

Read more: Hungary offers to host Russia, Ukraine peace talks