Lawyers representing 153 Sri Lankan asylum seekers on an Australian Customs ship say the men, women and children are being held against their will “behind locked doors”.

According to court documents lodged in the High Court, the Sri Lankans “do not have freedom of movement”, are living in rooms with no windows, are not aware of their location and families on the ship have been split up, with the women and children separated from their husbands and fathers.

A report in The Age also reveals that their possessions have been confiscated and they have been denied “reasonable access” to legal advice.

• ANALYSIS: why Australia is failing on asylum seekers

The documents form part of a High Court challenge against the Government’s powers to hold the asylum seekers at sea.

Lawyers are attempting to secure a High Court order that the Government cannot take the asylum seekers to a place other than Australia against their will.

While the Government is yet to file a defence, Immigration Minister Scott Morrison has told Parliament the asylum seekers are in good care.

“Any person who is in the care and protection of the Australian Customs and Border Protection Service will be in good care, and they are in good care,” he said.

In Parliament on Wednesday, Mr Morrison accused the opposition of being “a field of dandelions” when it came to border protection.

“What a bunch of jellyfish you are!” he said.

The asylum seekers are said to have left India early last month and were later transferred to a Customs ship, thought to be ACV Ocean Protector.

Lawyers for the asylum seekers have told the High Court the group does not want to be taken to Sri Lanka, Nauru or Papua New Guinea but want to be sent to Australia or another country that “has assumed the international law non-refoulement obligations”.

The case returns to the High Court on Friday.

-with ABC