A man threatened to behead his partner's daughter with a sword, before being tasered and pepper sprayed by police during a siege in Canberra overnight, a court has heard.

According to documents tendered to the ACT Magistrates Court on Saturday morning, officers were called to the couple's house in the Tuggeranong suburb of Wanniassa at 1:30am.

During the incident the man allegedly approached his partner with a sword and told her he was going to start "chopping c***s".

He specifically threatened to behead both her five-year-old daughter and mother.

The woman said the 28-year-old swung his weapon and took chunks out of the kitchen bench.

Police said the man confronted them when they arrived but he returned inside, locked the front door, and ignored their commands to open up.

Officers heard a woman and young children screaming and used a special tool to break down the door.

They smelled the strong odour of petrol and found the woman, her daughter and the alleged offender's two daughters, aged three and seven, in a "terrified state".

Five minutes after first arriving at the house, the police found the man hiding under a bed.

Officers tasered him after he allegedly violently resisted arrest and pepper sprayed him when they struggled to lock him into the police van.

'It's all lies,' accused says

The woman later told police the man began yelling when friends left their house.

During the incident the man allegedly pinned his partner against the wall and she only escaped by headbutting him.

The woman returned to the bedroom where the children began coughing because of the strong smell of petrol.

"I'm going to start killing c***s," the man allegedly said while holding a bowl of petrol.

She texted a man, who identified himself as her fiancé, to call the police.

The alleged offender sobbed in court as he was refused bail.

As guards led him out he called: "But it's all lies."

A prosecutor told the court the couple had been together for a month and moved in together a fortnight ago.