A group of refugees detained in Manus Island and Nauru will soon be told they have been accepted for resettlement in the US, the Australian government has confirmed.

The cohort of about 50 people is the first to be accepted by the US government under a deal struck between the former president, Barack Obama, and Australia to take up to 1,250 people.

“Representatives from the United States Resettlement Support Centre have started to provide some refugees with a decision relating to their US refugee admissions program application,” read a sign at the immigration detention centre, which asked people to be patient.

“Every case is different and moves through the required steps of the process at different speeds. This is only the first group of decisions and only some who have expressed an interest in US resettlement will receive a decision at this time.”

A number of detainees have received appointment slips with the USRSC for Wednesday and Thursday. It is not yet clear whether the appointments are all to tell people they have been successful, but prime minister Malcolm Turnbull said at least 50 people would be going to the US.

Turnbull, said about 25 people from Nauru and 25 from Manus would be informed of their upcoming resettlement in the US soon.

“President Trump had some reservations about it but, nonetheless, he is honouring the commitment made by his predecessor and I want to thank you for doing so,” he told the Seven Network.

“There are around 25 on each place, will be offered places in the United States. That’s the advice … There are many that are being vetted, but it is entirely up to the United States as to how many are taken.”

The Australian immigration minister, Peter Dutton, confirmed the reports on Wednesday morning and said the first group of refugees were expected to depart Manus and Nauru “in coming weeks”.

“Processing of other individuals continues and further decisions by US authorities are expected in due course.”

He said the refugee resettlement process “would not be rushed” and said he would not comment on the matter.

The deal with the US sought to end the indefinite situation for the hundreds of people sent to the offshore immigration detention centres after they attempted to seek asylum in Australia by boat.

Many refugees have spent years in the Australian-run centres, where they have been exposed to violence, death and high rates of mental illness and despair.

Upon taking office Trump balked at the arrangement, which he dubbed a “dumb deal”, but he reluctantly agreed to honour it.

That the deal never required the US to take any refugees – but simply assess them for potential resettlement – sparked some concern, as did an abrupt pause in processing when the US hit its annual immigration cap in July.

The 50 resettlements do not come close to assisting the almost 1,200 people on Manus and Nauru. More than 1,600 – including people who were transferred to Australia for medical treatment – have expressed interest in the US option.

The Australian government has floated a “third country” option for a number of years but appears no closer to finding one other than the US – which will not cover all required placements – or New Zealand, which the Australian government has rejected.

A $55m deal with Cambodia has largely been seen as a failure, with fewer than 10 transferred there and most abandoning their protection claim after a short time there.

A Refugee Action Coalition spokesman, Ian Rintoul, told the Guardian acceptance by the US for resettlement would be “welcome news” for refugees who received it. Most have been on the islands more than four years.

“But however welcome it may be for some refugees, it is also a bitter reminder that the US deal was never the solution that Malcolm Turnbull pretended it to be. The deal does not provide places for all those who need it.”

The Manus Island detention centre is slated for closure on 1 October and there is increasing pressure being brought to bear on refugees held there, with buildings shut, medical and other services scaled back and withdrawn, cigarettes banned, and power and water shut off, in an effort to encourage resettlement within Papua New Guinea.

The Nauru processing centre does not have a proposed closure date. But the president of Nauru, Baron Waqa, reaffirmed his country’s position that no refugees would be allowed to permanently resettle in Nauru.