Refugees inside the Manus Island detention centre have been told to leave, or they will be forced out by police.

Key points: Refugees told they will have to move from the facility in the "imminent future"

Refugees told they will have to move from the facility in the "imminent future" Centre managers warn refugees that police will be brought in if they don't move

Centre managers warn refugees that police will be brought in if they don't move Many refugees fear for their safety if they are moved to an alternative location

Men living inside one of the main compounds, Foxtrot, have been told to move today to a so-called "transit centre" closer to the town on the island.

The centre manager issued a letter to refugees saying they could go to other compounds, but would ultimately need to move out entirely.

"From July 26, 2017, the accommodation you have been afforded by the Government of Papua New Guinea in the Foxtrot Compound within the Manus Regional Processing Centre will cease," it said.

"For residents who have been determined to be a refugee you have been afforded by the Government of Papua New Guinea a new residence at the East Lorengau Transit Centre (ELRTRC), which you should make arrangement to move to.

"Alternatively if you elect not to go to the ELRTC today you can relocate temporarily to accommodation in Delta and Oscar compounds within the MRPC.

"However you will have to relocate in the imminent future to the ELRTC as the phased shutdown of the MRPC continues."

The letter that was sent to refugees informing them of the move. ( Supplied )

The letter warns that continuing to occupy state property could be an offence and that refugees could be referred to police if they stay.

It also warns that power, water and cleaning services will cease.

Many refugees do not want to move to the transit centre as they believe it is not safe and that the Papua New Guinean Government will not provide enough food and medical care.

A letter from almost 600 refugees on Manus Island to the Australian Government on July 24 pleads for resettlement in a safe country rather than relocation on Manus Island.

"There is no safety and security for us in the town as we have experienced time and time again," it said.

"We have been beaten up, robbed, humiliated and insulted by locals almost every single day."

The transit centre is also much smaller than the detention centre, with capacity for less than 300 refugees.

The refugees are waiting for resettlement in the United States, but that is unlikely to occur before October, the same month the centre is due to close.

The US reached its refugee intake cap earlier in July, and the intake does not reset until the start of October.

It is also possible that not all the men will be accepted and a large contingent could be left in PNG.

The Australian and PNG governments maintain that the centre will close by the end of October.