The Royal Australian Mint, an official supporter of the Games, has released 30,000 uncirculated AUD$1 (£0.50/$0.70/€0.60) coins which feature braille text - used by the visually impaired - spelling out "Sydney 18".

Also released are 2,018 AUD$5 (£2.70/$3.50/€3) silver selectively gold-plated proof coins, while a commemorative AUD$2 (£1/$2.30/€1.20) coin will go into circulation in time for the Games. 

"The coins celebrate the unconquered spirit that this community displays each and every day and that you will all witness when these Games begin," said Invictus Games Sydney 2018 chief executive Patrick Kidd.

"While these Games honour the sacrifice of all Australians who have given their lives for their country, they also recognise the many veterans who live amongst our communities as well as the families who are united by service in defence. 

"Above all they celebrate the incredible competitors who use sport as a vehicle to recover and rehabilitate and themselves are unconquered.

Royal Australian Mint chief executive Ross MacDiarmid added: "The coloured $1 collectible coin combines innovative colour print technology with braille text - a first for the Royal Australian Mint and for Australia - and has been released alongside a fine silver selectively gold-plated coin.

"Together these coins honour the service and sacrifice of those competing in the Invictus Games Sydney 2018 and are a tangible demonstration of the Mint's support of the event."

The fourth edition of the Invictus Games will take place from October 20 to October 27.

They were founded by British Royal Prince Harry and see wounded armed forces members compete.