Two teenagers have been extradited from interstate and charged with the alleged murder of a man in an apartment earlier this year.

Emergency services were called to the unit in the inner-southern Sydney suburb of Waterloo about 7.20pm on August 18.

Officers found a 34-year-old man with stab wounds who was taken to hospital in a critical condition.

He died around an hour later.

A 35-year-old woman, who with him at the time, was also allegedly attacked and suffered injuries.

Following an investigation, two men – both aged 18 – were arrested by Queensland Police at a property in Toowoomba and extradited to NSW.

They were each charged with murder and wounding someone with the intent of causing grievous bodily harm.

One of them was 17 at the time, NSW Police said, so will face Children’s Court on Friday.

Meanwhile, the other 18-year-old will face Bail Division Court.

Police then arrested a third man, aged 20, on Morehead Street in Redfern, in inner-city Sydney, on Thursday afternoon.

He was also charged with murder and wounding a person with intent to cause grievous bodily harm.

He is also due to face Bail Division court on Friday.

–AAP