By Andrea Shalal

WEST PALM BEACH (Reuters) -U.S. President Donald Trump said on Sunday he will impose secondary tariffs of 25% to 50% on all Russian oil if he feels Moscow is blocking his efforts to end the war in Ukraine, and they could start within a month if there is no ceasefire.

Trump told NBC News he was angry and "pissed off" when Russian President Vladimir Putin criticized the credibility of Ukrainian President Volodymyr Zelenskiy's leadership, NBC reported.

Trump told NBC News by phone that he planned to speak with Putin this week.

During his 2024 presidential campaign, Trump promised repeatedly to end what he calls a "ridiculous" war in Ukraine, and he has focused heavily on the issue since taking office on January 20. Trump himself has called for new elections in Ukraine and falsely called Zelenskiy a dictator.

Putin on Friday suggested Ukraine could be placed under a form of temporary administration to allow for new elections and the signature of key accords, which could effectively push out Zelenskiy.

"If Russia and I are unable to make a deal on stopping the bloodshed in Ukraine, and if I think it was Russia's fault ... I am going to put secondary tariffs on oil, on all oil coming out of Russia," Trump said.

"That would be, that if you buy oil from Russia, you can't do business in the United States," Trump said. "There will be a 25% tariff on all oil, a 25- to 50-point tariff on all oil."

He said the tariffs on Russian oil would come within a month without a ceasefire deal.

Trump said Putin knows he is angry with him, but said he had "a very good relationship with him" and "the anger dissipates quickly ... if he does the right thing."