An Australian man has been charged with terrorism offences after allegedly stabbing a man in a Sydney park in what police say was an Isis inspired attack.

Ihsas Khan has been charged with committing a terrorist act and attempted murder after allegedly stabbing Wayne Greenhalgh repeatedly as he walked through a park in the suburban Minto district of the city on Saturday afternoon.

The 59-year-old remains in a critical condition in hospital.

Khan also attempted to stab a police officer before he was arrested, police said.

The 22-year-old appeared at Parramatta Bail Court where he was refused bail.

He did not enter a plea and the case was adjourned until Wednesday. He faces life behind bars if convicted.

New South Wales Deputy Police Commissioner Catherine Burn said Khan and Mr Greenhalgh did not know each and said the attack was deliberate.

She said: "This was clearly a very volatile, a very violent situation that police and the members of the community were confronted with.

Terrorism in 2016: Terror attacks in Europe claimed by Isis Show all 9 1 /9 Terrorism in 2016: Terror attacks in Europe claimed by Isis Terrorism in 2016: Terror attacks in Europe claimed by Isis Policemen outside Rouen's cathedral during the funeral of Jacques Hamel, the priest who was killed in a church in Saint-Etienne-du-Rouvray in Normandy on 26 July during a hostage-taking claimed by Islamic State group Joel Saget/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Two jihadists, both 19, slit Hamel's throat while he was celebrating mass in an attack that shocked France as well as the Catholic Church Joel Saget/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Muslims place flowers and hold a minute of silence in front of the church if Saint-Etienne-du-Rouvray, western France, where French priest Jacques Hamel was killed on 26 July Charly Triballeau/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Two people hold each other by the new makeshift memorial in Nice, in tribute to the victims of the deadly Bastille Day attack at the Promenade des Anglais Valery Hache/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis The Islamic State group claimed responsibility for the truck attack that killed 84 people in Nice on France's national holiday. Mohamed Lahouaiej-Bouhlel, 31, smashed a 19-tonne truck into a packed crowd of people in the Riviera city celebrating Bastille Day Valery Hache/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Police work at a site where a Syrian migrant set off an explosive device in Ansbach, southern Germany, on 25 July, killing himself and wounding a dozen others Daniel Roland/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis A Syrian migrant set off an explosion at a bar in southern Germany that killed himself and wounded a dozen others in the third attack to hit Bavaria in a week. The 27-year-old, who had spent a stint in a psychiatric facility, had intended to target a music festival in the city of Ansbach but was turned away because he did not have a ticket Friebe/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Police officers walk along train tracks in Wuerzburg southern Germany on 19 July, a day after a man attacked train passengers with an axe. German authorities said they had found a hand-painted IS flag among the belongings of the man, an asylum seeker from Afghanistan, who seriously injured four members of a family of tourists from Hong Kong in his rampage Daniel Roland/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis German police killed a teenage assailant after he attacked passengers on a train in Wuerzburg, southerg Germany with an axe and a knife on 18 July, seriously wounding three people Karl-Josef Hildenbrand/AFP/Getty Images

"We know that this person has strong religious beliefs inspired by Isis. What made him act yesterday we don't know.

"This is the new face of terrorism. This is the new face of what we deal with".

She said Khan had shouted some words at the scene that made them suspect he was connected to the terror group.

Mr Greenhalgh’s wife Bronwyn, who witnessed the attack, said her husband had suffered a punctured lung and lost several fingers.

She told Australian news channel Ten Network: "He just came toward him and got a machete out of his backpack and started going at Wayne".

Commenting on the case, Prime Minister Malcolm Turnbull noted that the attack occurred the day before the 15th anniversary of the 9/11 terror attacks on the World Trade Center in New York.

He told reporters: "Connecting them both is a violent Islamist ideology".

It came after an 18-year-old was arrested outside the Sydney Opera House after allegedly telling security guards Isis had told him to carry out an attack there.

Counter-terrorism investigators charged the teenager with threatening to destroy property. Police said he was was carrying two canisters of automotive fluid.