Matthew Donaldson is arrested after being accused of trying to kill a woman at Sydney hotel

A man wanted over a brutal sledgehammer hammer assault on a woman inside a luxury five-star Sydney hotel has been discovered in bushland and arrested.

Matthew Donaldson was found at Lapstone in the NSW Blue Mountains just before 5pm on Thursday, almost two days after the alleged attack. 

He was arrested and taken to Penrith Police Station, where he is assisting police with inquiries.

Police put out an alert for the 41-year-old on Wednesday after a woman was allegedly seriously assaulted inside the Primus Hotel in Pitt Street Hotel in the CBD. 

A Belarusian woman was rushed to hospital after she was allegedly assaulted with a sledgehammer in a Sydney hotel room on Tuesday night. She is pictured on a stretcher being treated by paramedics

Emergency services had rushed to the Primus Hotel about 11pm on Tuesday after receiving a tip-off from an anonymous male caller. 

The woman was found unconscious and covered in blood. She was treated for head lacerations by paramedics at the scene, where disturbing images showed the woman hooked up to a respirator before being stretchered into an ambulance.

She was rushed to the Royal Prince Alfred Hospital in a critical condition but she is understood to be now in a serious but stable condition.

‘An unconscious female lying on the bed in the hotel, she had sustained serious injuries to her face and head, located inside the room is what police will describe as a small sledgehammer,’ Acting Superintendent Paul Dunstan said.

‘(She had) very significant injuries (and is) very fortunate to be alive, to be honest.’  

Investigators say it was likely the pair had never met before the alleged attack, with Donaldson meeting the woman in the hotel foyer before taking her up to his room.

Donaldson is believed to have left the hotel and headed to Wynyard train station before police arrived on scene.