Photographs of fresh bruising on Donald Trump's hand raised eyebrows on Thursday, but the 79-year-old president dismissed renewed speculation over his health, saying he had simply hit a table.

Trump has been seen with frequent bruising on his right hand since returning to the White House last year, often concealing it with bandages and makeup.

The White House has previously said it is due to a combination of frequent handshaking and the aspirin he takes for his cardiovascular health, which can lead to proneness for bruising.

However, photos on Thursday at the World Economic Forum in Davos, Switzerland showed a big, dark bruise in a similar location – but this time on Trump's left hand.

The images, taken while Trump was at an inaugural ceremony for his so-called "Board of Peace" initiative, quickly spread on social media.

"I clipped it on the table," Trump told journalists on Air Force One when asked about the bruising, adding: "I would say, take aspirin if you like your heart, but don't take aspirin if you don't want to have a little bruising."

The White House had earlier downplayed any concerns, giving the same explanation for the bruise.

Photos from earlier in the event and yesterday showed no bruising on the left hand.

Speculation has swirled about Trump's fitness given his age – he is the oldest person to take office as president – swelling in his legs, several moments of dozing off during public events, and deeply erratic behavior.

An unannounced hospital visit last year added to suspicions of secrecy around his health.

Weeks afterward, Trump's doctor said MRI imaging had shown the president to be in "excellent" cardiovascular condition, while the Republican has continued to make bombastic claims about his "perfect health."