The asylum seekers have been detained outside Australia's migration zone since their boat was intercepted on its way from India on July 7.

Stephen Donaghue, QC, representing the government, says the Commonwealth has no plans to send the asylum seekers to Sri Lanka.

Dr Donaghue told the High Court in Melbourne on Friday that the government would stick to its undertaking that no one on the boat would be sent to another country without three days' written notice.

Justice Kenneth Hayne said that given the asylum seekers were in custody it was important that the legal battle over their future ended as quickly as possible.

''The parties are just going to have to bend their back to get on with it,'' he said.

''I am not going to let this case devolve into a procedural morass. There's got to be some sense shown.''

Justice Hayne said the case appeared to come down to whether the government had the power to intercept the asylum seekers and take them to a country other than Australia.

Hugh De Kretser, executive director of the Human Rights Law Centre, said: ''We welcome the government's confirmation that it has no plans to return the people on the boat to Sri Lanka.''

Lawyers hope the case will be heard in full by early August, saying every day the case is delayed, the longer the asylum seekers, including 37 children, are left on the high seas.

''It's extraordinary that we still don't know what the government's plans for the people are,'' Mr De Kretser said.

It has been three weeks since Fairfax Media first made contact with the boat, which was leaking oil and headed towards Christmas Island.

The High Court case will resume on Tuesday.