President Volodymyr Zelenskyy’s security service said Monday, it foiled a coup that would have “played into Russia’s hands” as his Ukrainian forces battled their Russian counterparts in the east of the country.

News of the plot emerged ahead of the visit of one of Russian President Vladimir Putin’s only European allies, Hungarian Prime Minister Viktor Orbán, to Kyiv on Tuesday for talks with Zelenskyy.

The Security Service of Ukraine (SBU) said in a Telegram post on Monday that a group of people were preparing “a series of provocations” in capital Kyiv.

It added that the group was led by a co-founder of a public organization known for its “anti-Ukrainian actions” since 2015, although it did not name either the individual or the group.

After calling for a public gathering in central Kyiv on Sunday, the suspects were planning to announce the removal of the country’s military and political leadership from power, the SBU said. Then they plotted to seize the building of the Verkhovna Rada, Ukraine’s Parliament, the statement added.

The perpetrators “hoped to stir up the social and political situation within our country, which would work in Russia’s favor,” the security service said, although it did not explicitly say whether the Kremlin was behind the group or its plans.

The SBU did not identify the suspects or say how many people were detained. But it said they are facing charges of calling for and trying to overthrow the constitutional order and seize power. If convicted, they could face up to 10 years in prison, the SBU said.

In a separate statement, Ukraine’s Office of the Prosecutor General said Monday that the head of the group sought out members of the military and private security guards to help them carry out the plan.

It added that the leader rented a hall in Kyiv that could accommodate 2,000 people, although it did not specify what the hall was to be used for. It also said that four people had been detained.

NBC News could not independently verify the details of the alleged coup, one of several purported attempts to topple the Ukrainian leadership since Putin launched his invasion in February 2022.

Ukrainian investigators said in May that they foiled a Russian plot to assassinate Zelenskyy and other top military and political figures. Two colonels in the State Guard of Ukraine, which protects top officials, were detained on suspicion of enacting the plan.

And ahead of the Russian invasion, Zelenskyy claimed to have intelligence and recordings of a coup plot involving Russians and a Ukrainian billionaire oligarch.

News of the latest plot emerged two days before Orbán, Hungary’s Prime Minister, arrived in Kyiv for talks with Zelenskyy.

Orbán, a self-described “illiberal” leader, is known to have a close personal relationship with Putin and while he and his government have condemned the invasion of Ukraine, they have refused to criticize the Russian leader.

He has also routinely blocked, delayed or watered down European Union efforts to extend assistance to Ukraine and to sanction Russia over the war.

He has also accused Ukraine of infringing on the rights of an ethnic Hungarian minority in the country’s western region of Zakarpattia for years, complicating relations between the two neighbors.

Orbán’s visit comes the day after Hungary took over the six-month rotating presidency of the European Union, a position that has little real power but can be used to set the tone of the 27 nation bloc’s agenda.

And after gains by the far-right in voting for the European Parliament last month, Orbán on Sunday presented a new alliance with Austria’s far-right Freedom Party and the ANO party, the main Czech opposition, which hopes to attract other partners and become the biggest right-wing group.

“A lot has been done for this visit,” Ukrainian president’s chief of staff Andriy Yermak said Tuesday. “An important conversation about the future of Europe, security, international law, the Peace Formula,” he added, referring to Zelenskyy’s 10-point plan for ending the war.

Elsewhere, in eastern Ukraine, fierce battles between the country’s forces and their Russian rivals continued. However, Moscow’s counteroffensive in the northeastern Kharkiv region appeared to stall as newly-committed U.S. military supplies have started to trickle in.