US media are reporting that former US President Joe Biden has been diagnosed with an "aggressive form" of prostate cancer.

According to CNN and others, Biden's office released a statement on Sunday saying that the former president's cancer had spread to his bones, but appeared to allow for "effective management."

The reports say that the 82-year-old Biden was examined last week after experiencing increasing urinary symptoms. He was diagnosed with prostate cancer on Friday.

The statement says Biden and his family "are reviewing treatment options with his physicians."

Biden served as vice president under former President Barack Obama for eight years from 2009. He was elected president in 2020, beating the Republican candidate Donald Trump.

Biden sought reelection last year, but withdrew in July amid growing concerns about his health.

He was the first sitting president since Lyndon Johnson 56 years before to withdraw from an election after a single term.

Japanese Prime Minister Ishiba Shigeru said in a social media post on Monday that he was saddened by the news of Biden's diagnosis. He wrote that his "thoughts are with his family," and that he sincerely wishes him "a prompt recovery."