Prime Minister Scott Morrison has used a visit Christmas Island today to announce it is where asylum seekers currently on Manus Island and Nauru who are deemed "a risk" to Australia would go if they apply for a medical transfer.

Key points: The PM announced asylum seekers on Manus or Nauru deemed a risk to Australia will be sent to Christmas Island for medical treatment

The PM announced asylum seekers on Manus or Nauru deemed a risk to Australia will be sent to Christmas Island for medical treatment One local said the Government does not acknowledge the needs of the island's residents

One local said the Government does not acknowledge the needs of the island's residents No operations are normally carried out on the island and nobody has given birth there for decades

It was the first time a sitting prime minister has visited the external Australian territory, which geographically is closer to Indonesia.

Mr Morrison visited in 2011 as a shadow minister, alongside then-opposition leader Tony Abbott.

The PM recently announced the Christmas Island Detention Centre would reopen after legislation passed Parliament — against the Government's will — giving doctors a greater say over whether asylum seekers on Nauru and Manus Island are transferred to Australia for medical treatment.

He said anyone on Manus or Nauru deemed a risk to Australia would be sent to the centre's high security North West Point facility if they apply for a medical transfer under the legislation.

It is understood that cohort includes 57 men currently on Manus and Nauru, some, allegedly charged with murder, inappropriate behaviour or terrorist activity.

Mr Morrison rejected suggestions his presence on Christmas Island and the re-opening of a detention centre would encourage people smugglers to re-start their trade.

"Any of those who would seek to try and game this arrangement that has been put in place by the Australian Parliament with Labor's cheering it on, well, you won't be coming to the mainland of Australia, you'll be coming here," he said.

Locals said there had been an influx of police and security staff on Christmas Island since Mr Morrison announced the detention centre would be reopened.

Christmas Island taxi driver Chris Carr said it had been good for some local businesses.

"The restaurants are benefiting and the drinking establishments, the supermarket and such," he said.

Chris Carr said the Government did not listen to residents. ( ABC News: Jon Sambell )

Ads have recently been placed for more medical staff, but as it stands, Mr Carr — whose son has autism — said the island was not equipped to deal with sick asylum seekers.

"We haven't got the proper mental health workers up here and the only time we ever do get them is when [the private service provider] SERCO comes up with the refugees," he said.

"I've got nothing against the refugees, don't get me wrong, but it's the Government that I have problems with because they don't listen to us, they don't acknowledge what our needs are and everybody else's needs come before ours."

Jon Stanhope was the Commonwealth-appointed administrator on Christmas Island from 2012 to 2014, and said he did not think it was set up to deal with ill asylum seekers either.

"The decision is truly bizarre, it's a very strange decision, a decision that's driven very much by politics and not by practicalities," he said.

"No operations can be done on Christmas Island, women haven't given birth on the island I think for some decades now, there's a very minimal level of services in the hospital as currently configured and staffed.

"The majority of residents of Christmas Island that have health issues travel to Perth, indeed some of the islanders of Malaysian or Chinese heritage actually do go to Singapore or to Malaya for some of their health services, I know many of the members of the Malay community have their dental needs met by dentists in Malaya."

The announcement of the reopening of the detention centre has seen an influx of arrivals. ( ABC News: Jon Sambell )

Mr Stanhope is also a former Labor chief minister of the ACT, and while he believed Mr Morrison's decision to reopen the centre was a political one, he said he wanted more scrutiny of Labor's position.

"It's a decision that's been driven I believe by the Prime Minister's desire to respond to the fact that he lost control of an issue, that he now wants to look tough, he wants to look like he's in control of the issue of asylum seekers coming back to Australia, he wants to look tough in the context of a debate about border patrol," he said.

"But I also believe it's convenient for the Labor Party.

"I never forget that it was my party, the Labor Party, that sent asylum seekers to Nauru and Manus almost six years ago and the Leader of the Opposition Bill Shorten and his colleagues within the Labor Party have found it a very convenient distraction from questions about, 'Well if you do win the election Mr Shorten, exactly what are you going to do about the almost 1,000 asylum seekers left on Manus and Nauru'."

Already a variety of advocacy organisations, including Amnesty International and the Human Rights Law Centre, have banded together and formed a group they said would work with doctors to ensure sick people on Nauru and Manus island were flown to Australia quickly.

The key question is whether those not deemed a risk will be sent to Christmas Island or to the mainland.