An Australian navy vessel brought 20 Sri Lankan asylum seekers to the Christmas Island detention centre where they were held for a number of days before being sent home on Wednesday, according to a report.

It marks the first time in five years that asylum seekers attempting to reach Australia by boat have been taken by sea to Christmas Island, which lies 1500 kilometres north west of the mainland.

Prime Minister Scott Morrison visits the detention facilities on Christmas Island after reopening the centre. Credit:AAP

The Department of Home Affairs confirmed authorities had returned 20 asylum seekers to Sri Lanka after intercepting a people smuggling voyage.

"Australian authorities recently intercepted an attempted illegal people smuggling venture from Sri Lanka," a spokesman said. "Twenty people aboard the vessel have been returned to Sri Lanka after attempting the dangerous and illegal voyage."