The Islamic State terror group (Isis) has challenged Prince Harry to fight the terrorists threatening it would send him and his Apache helicopters to "hellfire".

A Singaporean fighter made the threats in a video the group released at the weekend.

"Why don't you come here and fight us if you're man enough, so that we can send you and your Apaches to hellfire, biidhnillah [Allah permitting]?" the fighter said in the video, according to SITE Intelligence Group, which monitors terrorists' activities.

The warning came three months after Prince Harry went on a two-day official visit to Singapore.

During the visit, the prince delivered a speech to pay homage to the victims of the London Bridge terrorist attack, in which seven people were killed in June. Isis claimed responsibility for this and other attacks occurred on British soil in the past few months.

"To Harry, you come to Singapore and tell such stories to gain sympathy for the London terror attacks?" the Isis fighter is also heard saying in the video, according to local newspaper The Straits Times.

Prince Harry served in the military for ten years. Among other duties, he served with the British Army in Helmand, Afghanistan for more than two months in 2008.

It is believed this is the first time that an Isis video features a Singaporean fighter.

Singapore's interior ministry identified the man as 39-year-old Meghat Shahdan bin Abdul Samad. It is believed the man travelled to Syria to join Isis after he became radicalised while working in the Middle East.

British Army leaves Afghanistan
Prince Harry salutes as the Last Post is played as he joins British troops and service personnel for a Remembrance Sunday service at Kandahar Airfield Matt Cardy/Getty Images

The Isis fighter also urged Muslims to travel to East Asia and join their fight there, SITE said.

The plea comes as the group is losing key territories in Syria and Iraq.

When Isis emerged in 2014, it seized large territories across both of the Middle East countries, making Mosul in Iraq and Raqqa in Syria the respective capitals of its self-declared Caliphate. The group has now lost most of the territories due to regional offensives led by international coalitions.

The latest video, published by Isis media wing Al Hayat Media Centre, is believed to be part of a propaganda series called Inside The Caliphate.

Earlier this year, Isis released another video calling on Muslims to join a group's cell in the Philippines, where the army is engaged in a fierce battle against thew militants to liberate the besieged town of Marawi.

Earlier this month, British military officials said Isis is still able to carry out attacks in the West despite the fact it has lost several territories in Syria and Iraq

The remarks came days after Isis claimed responsibility for a botched bomb attack that left 30 people injured on a train at Parsons Green station, in West London.

The group often claims responsibility for attacks occurred throughout Europe on its news agency Amaq. However, experts say it does not necessarily mean that Isis is behind every attack and claiming attacks might just be a way to boost propaganda and increase recruitment.