The donors are required between December 16 and January 6, 2020.

To celebrate the 'Secret Santa' exchange, blood donors at Australian Red Cross Lifeblood will not only receive a card to give someone special letting them know that they gave blood on their behalf, they will also be giving someone somewhere the most precious gift they've ever received.

Lifeblood spokesperson Brian Bruce urged locals to give blood, saying it was the most important 'Secret Santa' they'll ever do.

"A total of 934 donors are needed to prevent a possible shortage of blood stocks vital to the treatment of cancer patients," he said..

"With many people taking time off this holiday season we need those who can to step up and be a life-changing 'Secret Santa' to Australian patients in need, ensuring no one misses out on receiving this incredible gift.

"If Secret Santa is about giving anonymous gifts designed to make someone's day, then blood donation really is Australia's ultimate Secret Santa exchange."

Blood will be needed by road accident patients, pregnant mums, cancer patients and even premature babies every day over Christmas and New Year.

Mr Bruce said stocks of platelets, a blood component vital to the treatment of cancer patients, were particularly at risk during the holiday period.

"It takes four blood donations to make just one bag of platelets for patients and they only last for five days so donors are constantly needed to ensure cancer patients get this vital product.

"Your blood donation will be the ultimate gift to Australian patients this Christmas - and will have a far-reaching impact on the lives you save, and the lives of their loved ones.

"So this Christmas we're urging Newcastle locals to take part in Australia's Biggest Secret Santa exchange by making an appointment to give blood between December 16th and January 6th."

To make an appointment to give blood or find out more about Australia's Biggest Secret Santa, call 13 14 95 or visit lifeblood.com.au.