Australian Border Force needs to ‘front up’ and explain how a convicted rapist being detained at a Darwin detention centre was able to escape while on a day trip to an aquarium, the chief minister says.

Amit Hamal, 27, who claimed to be a member of the Nepalese royal family, was working as a delivery driver for an Indian restaurant in Sydney when he raped a 44-year-old woman asleep in her home in 2010.

He was convicted of sexual intercourse without consent and sentenced to three years in prison with a non-parole period of 18 months.

Since his visa was cancelled Hamal has been in detention resisting deportation to Nepal.

He was part of a group of detainees from the Wickham Point detention centre released on a May Day excursion to Crocosaurus Cove in Darwin’s CBD, when he fled the aquarium at about 11am on Monday, before being recaptured by police before 7pm.

‘Police did a tremendous job in recapturing this person but I think Border Force have some answers that they need to front up and explain how this was allowed to occur,’ Chief Minister Adam Giles told reporters on Tuesday.

‘This is at the same time as the federal government is saying they don’t want to extend the police agreement with the NT and we’re seeing escapees out of the detention facility.’

Following riots at the detention centre in 2010, the federal government agreed to fund 94 NT police officers as part of the metropolitan response group to handle issues at the centre.

That funding has since been taken over by the NT government while negotiations to extend it continue with Canberra.

Mr Giles called on the federal government to make Darwin’s detention centre the primary one for mainland Australia, suggesting there could be more escapes if there was not enough funding to maintain policing.

‘Darwin is the front line of defence of northern Australia, and at the time when the federal government is closing detention centres around this nation they must keep the Darwin detention centre open. They must keep the financial agreements with the police force of the NT so that we can provide the appropriate policing services for the right security measures at the detention facility,’ he said.

‘Whether that is full, empty or half-occupied, you’ve got to be able to resource that and you’ve got to get the right policing levels to be able to support that.’ Border Force has been contacted for comment.