Scott Morrison has defended spending $185 million reopening an immigration detention centre before promptly shutting it down again.

Mr Morrison reopened the mothballed Christmas Island facility after ‘medevac’ legislation was passed to make it easier for sick refugees on Manus Island and Nauru to obtain medical transfers.

Mr Morrison did not agree with the legislation, but did not have the numbers to stop it.

Instead, he sent 140 contractors and 14 medical staff to Christmas Island, warning of the looming influx of sick refugees.

But there are none to look after, and there have been none in the six weeks the site has been reopened.

In fact, there has been just one person evacuated since the new laws took effect, and that person came straight to Australia because they required a level of medical care not available on the small remote island.

The Government now faces claims that reopening the facility was an alarmist and expensive mistake.

Scott Morrison says the centre is doing its job.

“It is providing a deterrent to those who would have looked to game the system,” he told reporters over the weekend.

Treasurer Josh Frydenberg dismissed the criticisms too.

“Whether it's in our turn backs, whether it's in offshore processing or whether it's with Christmas Island, we are absolutely focused on ensuring there is no repeat of Labor's disastrous border protection policies,” he told the ABC.

Whether it was a waste of money could be a matter of perspective.

“You could see it the other way around, which is, the so-called emergency that everyone was talking about hasn't actually eventuated,” Mr Frydenberg said.

The government has outlined plans to repeal the medical evacuation laws and close Christmas Island if it wins the upcoming election.