Doubling of detained immigrants due to genuine asylum seekers

The number of people held in Australia's immigration detention centres almost doubled last financial year, with a 97% rise on the back of mostly genuine asylum seekers.

Figures released in the Department of Immigration's annual report show the number of people held in the detention network rose from 7252 last year to 12,027 on June 30 this year.

The vast majority of new arrivals in both on and offshore detention centres were refugees arriving by boat - then called "irregular maritime arrivals", now referred to as "illegal" under the current government.

Of the total 12027 in detention centres, 11,402 arrived by boat, 162 were "unauthorised air arrivals" and 371 were living here without a visa, while the remaining 92 has visas cancelled or were stowaways and ship deserters.

The data also shows some 58 babies were born to "clients in community detention" last financial year, up from 51 babies born in detention in 2011-12.

Of those taken to Australia's offshore detention centres last fiscal year, 18,999 were men, 2690 were women, and more than 4000 children were held in offshore centres.