Prime Minister Tony Abbott is refusing to say where a group of 153 asylum seekers are being held by Australian authorities, or whether they will be returned to Sri Lanka.

In the High Court on Tuesday the government promised to give three days notice before trying to return the group.

During the hearing the government for the first time confirmed their existence, after a week of speculation about their fate.

The group, which includes children as young as two, was intercepted at sea en route to Australia but won’t be processed under the Migration Act because they never entered territorial waters.

The asylum seekers are being held aboard a Customs vessel outside Australian territorial waters, but on Wednesday Mr Abbott refused to confirm their exact location.

“I won’t talk about on-the-water operations. That’s to give aid and comfort to people smugglers. That’s not something that I’m going to do,” he told the Nine Network.

He also would not say the asylum seekers won’t be returned to Sri Lanka.

“I will confirm today, as we always will, that we will operate in accordance with our legal obligation, and we will operate in accordance with safety at sea,” he said.