A bishop was stabbed while livestreaming a church service in Sydney, Australia, on Monday - the country's second knife attack in less than three days.

Bishop Mar Mari Emmanuel was one of four people injured in the attack at the Christ the Good Shepherd church in the Wakeley area of the city. 

He belongs to the Assyrian Orthodox Church and New South Wales police have said the alleged knifeman was known to the congregation. 

Video footage shows members of the congregation rushing to defend the bishop and restrain the alleged assailant.

A police statement said: "A police operation is under way in Wakeley, following reports of a stabbing.

"Officers attached to Fairfield City Police Area Command attended a location on Welcome Street, Wakeley, following reports a number of people were stabbed.

"Officers arrested a male and he is assisting police with inquiries."

Chris Minns, the premier of New South Wales, said: "My thoughts and prayers are with the victims and first responders who are working to keep us safe.

"It's important that the community remain calm and continue to listen and act to the directions of police and emergency services.

"We are a strong community in NSW and it's important that we all stick together, particularly in the face of adversity."

The attack happened as the country continues to reel from a stabbing rampage at the Westfield Bondi Junction shopping centre in Sydney on Saturday. Six people died in the attack.

The attacker, named as Joel Cauchi, was shot dead at the scene. It is reported that he had suffered from mental health issues.