Prince Harry announced Tuesday he is to leave the British army after 10 years' service that has seen him twice fight on the front line in Afghanistan.

The 30-year-old said it had been a "really tough decision" to end his military service in June, but added that he was looking forward to the next chapter in his life.

His decision will come as a surprise to many royal-watchers as the prince was living out his boyhood dream and seemed quite content with the army life.

Harry, who will be pushed down to fifth in line to the throne by his brother Prince William's second child, due in April, will end his military service after a four-week secondment to the Australian Defence Force in April and May.

"I am considering the options for the future and I am really excited about the possibilities," he said, in a statement released by his Kensington Palace official residence.

After his time with the Australian military, the prince will undertake an official tour of New Zealand, and then spend time doing voluntary conservation work in sub-Saharan Africa.

Before the end of the year, he will begin volunteering with the British Ministry of Defence's recovery programme supporting the rehabilitation of wounded, injured or sick service personnel, a subject close to his heart.

However, he is keeping his long-term options open, though he will continue to carry out royal duties on behalf of his grandmother Queen Elizabeth II.

Harry graduated from the elite Sandhurst military academy and served twice in Afghanistan, once on the ground and once flying attack helicopters.

A captain commissioned in the Household Cavalry, he currently has a desk job organising commemorative army events in London.

"After a decade of service, moving on from the army has been a really tough decision," he said.

"I consider myself incredibly lucky to have had the chance to do some very challenging jobs and have met many fantastic people in the process.

"From learning the hard way to stay onside with my colour sergeant at Sandhurst, to the incredible people I served with during two tours in Afghanistan -- the experiences I have had over the last 10 years will stay with me for the rest of my life. For that I will always be hugely grateful."

Harry is the younger son of Prince Charles, the heir to the throne, and the late Diana, princess of Wales.