A man has died after being found unconscious at Maribyrnong Immigration Detention in Victoria.

Police have begun an investigation into the circumstances surrounding the death which happened earlier on Thursday night.

The man had not arrived in the country on an asylum seeker boat but had been detained in January after overstaying his visa, a statement from Immigration Minister Scott Morrison said.

The Minister has expressed his sympathy to the man’s family and friends and pledged to provide support to authorities to help their investigations.