A holy bidding war for an `authentic skullcap’ worn by Pope Francis has ended with a bid of more than £12,000 in an online auction – half the sum estimated.

According to online auction house, Catawiki, the auction of the famous white cap “attracted attention from around the world and was finally sold to an American collector for £12,593”.

A spokeswoman said a “significant portion of proceeds donated to the charity Save a Child’s Heart”.

The original `auctioneer’s estimate for the item was between £19,550 and £25,420.

However, Catawiki’s devotionalia expert, Frederick Jamees said the new owner has purchased something extremely special, The Irish News reported.

“It seldom happens that the Pope’s clothes come onto the market, additionally the Pope’s garments automatically become relics after his death and it is forbidden to sell them,” he said.

“Therefore this auction was a unique opportunity to gain possession of a relic in the making. If the new owner wants to sell the skullcap he can only do so as long as the present Pope is alive.”

The Pope was passing through crowds at St Peter’s Square during his regular audience in 2014, when the TV host reached out offering a new skullcap.

It became a famous moment in Italy when footage of the moment was broadcast showing the Pope carefully inspecting the hat before swapping it with his own, and was documented by the Italian media.

The practice of prelates gifting their hats to a faithful in an exchange began in the modern era with Pope Pius XII and it has been continued by Popes John Paul II, Benedict XVI and Francis.