Just days before the deadly riot in the Manus Island detention centre last month, a Papua New Guinea man working in the camp's catering section beat up an asylum seeker in the dining area.

The incident is believed to have contributed to tensions between the detainees and locals employed in and around the centre.

Fairfax Media has been told the local was employed in the catering section operated by international provider Eurest.

A spokeswoman for Immigration Minister Scott Morrison confirmed this week an incident had occurred. She said Mr Morrison was advised of an incident that was ''initiated by a transferee striking a member of staff of one of the service providers at the centre''.

''The transferee was treated by International Health and Medical Services for a small cut as a result of the altercation,'' the spokeswoman said. She did not provide further details.

Asked if the matter would be included in the investigations, she said: ''Any and all events that are considered by [former public servant] Mr [Robert] Cornall to be relevant to the incident that occurred at Manus Island on the night of February 17, will be addressed in his independent review.

''The government expects that service providers conduct themselves lawfully and consistent with the service standards set out in their contract.''

A source at the centre said the bashing happened after the asylum seeker tried to pull a plastic glove off the hand of the caterer a week or so before the riots.

''He also tried to cut [the caterer] with a plastic knife and he slapped him. [The caterer] then bashed [the asylum seeker],'' said the source, who asked not to be named as comment by staff was banned.

Fairfax had previously been told locals working as caterers might have helped quell the riot and clashed with asylum seekers.

Eurest said ''it would not be appropriate for Eurest to comment on operational matters'' while there was a review. Eurest also declined to reveal whether the staff member in the bashing incident was disciplined or removed from the site.

The source said the local catering staff were no longer working in the centre alongside detainees, possibly because of the bashing.

But he said local cleaning staff were back in the centre because ''the expats got tired of cleaning the toilets''.

Eurest's website says the company promotes a corporate responsibility that promises to run the business in a way that ''reflects our values, connects our business decisions to ethical, social and environmental concerns''.

A number of rumours about who was responsible for the death and the assaults during the riots have circulated, including that locals piled in to help overwhelmed guards, that riot police shot at asylum seekers and that the asylum seekers were stomped on.

But so far none of the allegations has been confirmed by officials.

At least five inquiries are said to be under way into the riot that left asylum seeker Reza Barati dead and more than 70 injured, including one with gunshot wounds.

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