Washington, United States — Joe Biden had never been diagnosed with prostate cancer before last week and previously had a blood test for the disease 11 years ago, a spokesperson for the former US president said Tuesday.

The statement came after Biden's successor, President Donald Trump, fueled claims of a cover-up by saying that he was "surprised" the public was not told about the cancer earlier.

Biden's office announced on Sunday that the 82-year-old had been diagnosed with an aggressive form of prostate cancer, a few days after a nodule was found on the gland.

"President Biden's last known PSA was in 2014," a Biden spokesperson said in a statement to AFP. 

"Prior to Friday, President Biden had never been diagnosed with prostate cancer."

Prostate cancer, the most common among men, can be caught in its early stages using blood tests that measure for a protein called prostate-specific antigen, or PSA. 

Republican Trump has long bashed his bitter Democratic rival about his health and cognitive fitness.

And Trump and his allies have now raised questions about when Biden and his doctors knew about the cancer, given its advanced nature and the intensive medical scrutiny of US presidents.

But annual PSA screening after the age of 70 is not universally recommended.

The US Preventive Services Task Force advises against it, reasoning that the risk of false positives and the harms from biopsies and treatment outweigh the benefits.

Biden would have been aged between 71 and 72 at the age of the 2014 test.

Medical experts interviewed by AFP said the late identification of an advanced cancer would not be unheard of, even for a former president receiving top-of-the-line medical care.

Biden's office did not say whether the former president had separately been given prostate exams.

Questions over Biden's health dogged him throughout his curtailed reelection campaign and have been renewed in recent weeks ahead of the release of a book detailing what it calls his declining physical condition.

The ex-president expressed gratitude on Monday for an outpouring of "love and support" following his cancer diagnosis. 

Meanwhile, Trump and his son have publicly speculated — without presenting evidence — that Biden’s cancer was kept from the public, further fueling partisan tensions over the former president’s health.