WARSAW - Former Ukrainian President Petro Poroshenko says he is returning to Ukraine to fight treason charges - even though he views them as politically motivated - because he believes that fighting them is part of his defense of national unity.

Poroshenko spoke Sunday at a news conference in Warsaw hours before he is to fly Monday from the Polish capital to Kyiv, Ukraine, where he is to face the allegations in court.

A prosecutor has alleged that Poroshenko, one of Ukraine's richest businessmen, was involved in the sale of large amounts of coal that helped finance Russian-backed separatists in eastern Ukraine in 2014-15. He is owner of the Roshen confectionery empire. The Kyiv court has already frozen Poroshenko's assets as part of its investigation into the allegations of high treason.

Poroshenko insists that he is innocent. He accuses his successor, President Volodymyr Zelenskiy, of seeking to discredit him politically to distract from Ukraine's widespread problems, including economic woes and rising deaths from COVID-19.

'I will return to Ukraine to fight for Ukraine,' Poroshenko said, adding that he considers fighting the 'politically motivated' charges to be part of his patriotic fight for the nation.

Despite the seriousness of the charges, Poroshenko seemed upbeat Sunday. When asked by a reporter if he expects to be arrested upon his return home, he answered, 'Definitely not.'

The charges are the latest in a string of accusations leveled against Poroshenko since he was defeated by Zelenskiy in 2019. The allegations have generated concerns of undemocratic score-settling in Ukraine and alarmed Ukraine's allies. They come as Russia has built up troops along the Ukraine border and the United States has voiced concerns that Russian President Vladimir Putin might be planning an invasion of Ukraine.

Poroshenko said he sees charges he faces as harmful for the country at such a time. He said Ukraine's leadership is responsible for national unity, and what 'Russia is really looking for is disintegration and conflict inside the country.'

'I think this is a very irresponsible action of the current leadership to disintegrate the country and ruin the unity,' he said.

Poroshenko was defeated by voters following a corruption scandal and a mixed record on reforms, but he emerged with strong credentials a patriot for his work in rebuilding the Ukrainian army as it fought Russia-backed insurgent fighters in the east.

For his part, Zelenskiy says he is waging a fight against oligarchs that is aimed at reducing their influence in Ukraine's political and economic life.

Poroshenko has been outside of Ukraine for weeks, meeting with leaders in Brussels, Berlin and other European capitals.