Former Ukrainian President Petro Poroshenko dismissed what Moscow has called "referendums" in occupied Ukrainian territory as a "Russian trick," orchestrated by the Kremlin as a way to "legitimize" the presence of Russian troops.

"This is definitely not a referendum ... It's impossible to organize a referendum like that within 48 hours," Poroshenko told DW. 

Poroshenko, one of Ukraine's wealthiest businessmen, is the leader of the conservative European Solidarity party, and was Ukraine's president between 2014 and 2019. 

The Moscow-backed votes are being held in the regions of Kherson and Zaporizhzhia in the south and southeast, and in the Luhansk and Donetsk regions that make up Ukraine's eastern Donbas. The regions of Donetsk and Zaporizhzhia are only partially under Russian occupation.

The Russia-backed "referendums" come as Ukrainian forces have made considerable gains in eastern Ukraine, recapturing wide swathes of territory.

The self-declared "peoples republics" of Donetsk and Luhansk have been occupied by Moscow's proxies since 2014.

Russia annexed the Crimean Peninsula in 2014 following a referendum that lacked international recognition and which Kyiv considers illegitimate.

Poroshenko said he was confident that Ukraine's constitutional court would rule the referendum unconstitutional, just as was the case under his presidency, when Russia organized a vote on the annexation of Crimea.

'Nuclear blackmail'

The former Ukrainian leader also warned that Moscow could use the so-called referendums to justify launching an attack, including a nuclear attack, from annexed territories.

When asked about the likelihood of Moscow launching a nuclear strike, Poroshenko called Putin a "crazy maniac," who uses various forms of blackmail, including "nuclear attack blackmail."

Poroshenko stressed that Kyiv gave up its "nuclear arsenal" in exchange for security assurances, referring to the 1994 Budapest Memorandum.

Kyiv handed over Soviet-era nuclear weapons to Moscow and joined the Treaty on the Non-Proliferation of Nuclear Weapons in light of the memorandum, which was signed by Russia, the United States and the United Kingdom.

However, Poroshenko argued that Putin would not use nuclear weapons if Western states committed to a "severe" response to any attack.

He called for a joint declaration by nuclear powers that there would be a "quick and decisive reaction" to a Russian nuclear strike.

Poroshenko urged the world not to be "afraid" of Putin. "If you are weak, Putin [will] go as far as we … allow him to go," he said.

"Don't trust Putin," he said, claiming that Russia's president will "never keep his word."

More military help from Germany 

Referring to the German Bundestag's decision not to supply Kyiv with battle tanks, Poroshenko said that he was "disappointed" in Berlin.

"The more weapons, the more ammunition you supply, the shorter the way to peace," Poroshenko said, asking Germans to provide Ukraine with additional military support.

Poroshenko added that Kyiv "definitely" needs German tanks and ammunition given the current situation in Ukraine, but does not need German soldiers. "Help us save you, help us save Europe," he pleaded.

By supporting Kyiv, German is "investing in [its] own security," Poroshenko said. 

Edited by: Wesley Rahn