Former US Vice President Joe Biden speaks during a rally in Philadelphia May 18, 2019. (Xinhua/Liu Jie)

 
US Democratic presidential candidate Joe Biden, who President Donald Trump accused of involvement in a corruption case in Ukraine, called for the president's impeachment Wednesday.

"He should be impeached," Biden said of Trump at a rally in Rochester, New Hampshire, the first time he has urged Trump's removal from office since the alleged presidential misconduct related to Ukraine erupted.

"With his words, and his actions, President Trump has indicted himself by obstructing justice, refusing to comply with the congressional inquiry," said Biden, also former vice president of the United States. "He's already convicted himself in full view of the world and the American people."

Trump has been facing an ongoing impeachment inquiry led by House Democrats into what investigators believed to be his inappropriate interactions with Ukraine.

In a phone call with Ukrainian President Volodymyr Zelensky on July 25, Trump asked his counterpart to investigate Biden and his son Hunter Biden, according to a rough transcript of the call released by the White House. In response, Zelensky pledged that his government will look specifically into Burisma Holdings, a Ukrainian gas company accused of corruption, which Hunter Biden once worked for,

Biden has denied any wrongdoing, insisting that he has never spoken with his son about the latter's overseas business dealings.

"Donald Trump has violated his oath of office, betrayed this nation, and committed impeachable acts. You know, to preserve our Constitution, our democracy. Our basic integrity. He should be impeached," Biden told the audience in Rochester.

The controversy surrounding the Trump-Zelensky phone call also involved Trump's order prior to the call to put US military aid to Ukraine on hold.

In addition, Trump also requested that Zelensky do the United States a "favor" by finding out "what happened with" the computer server used by the Democratic National Committee that investigators probing alleged Russian interference in the 2016 US election believed was hacked by Russia. "The server, they say Ukraine has it," Trump told Zelensky, the transcript showed.

Reacting quickly to Biden's remarks, Trump tweeted that it was "so pathetic to see" his political rival "calling for my impeachment."

"I did nothing wrong. Joe's Failing Campaign gave him no other choice!" he added, linking Biden's assertions to the 2020 presidential election.

The president tweeted last Friday that his request for an investigation into Biden "has NOTHING to do with politics or a political campaign against the Bidens. This does have to do with their corruption!"

There has so far been no evidence of wrongdoing by either Biden senior or junior.

However, the former vice president, during an event in January 2018 at the Council on Foreign Relations, bragged about how he in 2016 successfully persuaded the Ukrainian authorities to sack the country's then prosecutor general, Viktor Shokin, who was investigating Burisma Holdings at the time.

Biden threatened to withhold some 1 billion US dollars in loan guarantees from Ukraine if Shokin was not removed. Shokin, in turn, was fired.