Four more immigration detention centres in Australia are set to be mothballed.

The federal government has patted itself on the back for stopping the flow of asylum seeker boats and has hailed the closure of its 17th detention centre in three years.

In Tuesday’s budget the government announced the Maribyrnong detention centre in Melbourne, the Blaxland compound at Villawood in Sydney, and Perth immigration residential housing will shut.

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The lease for the Wickham Point centre in the Northern Territory won’t be renewed beyond November 2016.

These closures will save the federal government close to $40 million over four years.

The domestic asylum seeker population in detention has plummeted from 6400 in September 2013 to less than 1700 as of April this year.

The North West Point facility at Christmas Island will be put into contingency from January 2018.

The federal government expects to raise money from the sale of Commonwealth-owned land at Maribyrnong and Villawood, but won’t say how much for commercial confidentiality reasons.

Offshore detention centres will receive an extra $61.5 million next financial year for operational costs as well as increased taxes.

No breakdown was available on how much will go to Nauru or Manus Island in Papua New Guinea, the latter which is slated for closure.

There is $55.4 million on the table for Indonesia to provide assistance to thousands of asylum seekers stuck in limbo there, unable to make it to Australia by boat.

The humanitarian refugee intake will remain at 13,750 places for refugees next financial year and it will increase to 18,750 by 2018-19.

The permanent migration program stays at 190,000 places, including 128,550 for skilled workers, 57,400 for family reunions.

There will also be almost 3500 for children coming to Australia for adoptions.

The immigration department is set to lose 305 staff in 2016-17.

-AAP