A total of 18 Bangladeshi asylum seekers are on hunger strike at a Darwin detention centre in Australia, Sky News reports quoting refugee advocates on Friday.  

The hunger strike began on Monday, with many participants also refusing water, according to Ian Rintoul of the Refugee Action Coalition.

He said most of the protesting Bangladeshi asylum seekers have been in detention for about three years.

One of the men was hospitalised for suspected dehydration on Wednesday night, although he has since been returned to the Wickham Point Detention centre, while another two were treated by the medical provider inside the centre, Ian Rintoul said.

They are protesting because they have not been offered bridging visas despite being in long-term detention, he says, while acknowledging the hunger strikers are at different stages of having their claims processed.

Up to 80 asylum seekers in Wickham Point have been released on bridging visas over the past few weeks, with 30 released on Tuesday, reports Sky News.

'They've got nothing, they've got no bridging visas, they've listened to their case managers for years, they've talked to people who visited, they've tried to make applications, some of them have got applications for temporary protection visas, for example, and still nothing happens', Ian Rintoul said.

'People just get to the point where they have got nothing else and it's the only way they can draw some attention to their plight.'

The Department of Immigration has been contacted for comment.