Scott Morrison and Peter Dutton have both been forced to defend their decision to release information surrounding the interception of a sixth asylum-seeker vessel from Sri Lanka since May.

"It's just a simple fact," the prime minister told reporters in Sydney on Monday.

"We have regularly released this information after these incidents have occurred. And it's a reminder, frankly, of the reality of the situation that this government deals with on a day-to-day basis."

Asked whether boat arrival details would now be released on a routine basis, he said: "The government releases information as it believes it's important to do so."

The home affairs minister has long been reluctant to comment about "on-water matters" regarding asylum-seeker vessels.

But confronted with a campaign to let a Tamil family stay in Australia, the government has released new information about an apparent surge in boat arrivals from Sri Lanka.

The latest vessel was intercepted west of Christmas Island on August 7, with 13 suspected asylum seekers flown back to the south Asian country on August 18.

Mr Dutton denied the information was released in order to help make a political point.

"We need to remind ourselves this is significant. People smugglers are watching everything that happens in Australia. I'm determined that we don't have any death at sea," he told the Nine Network.

But Labor frontbencher Joel Fitzgibbon said the motivation was clear.

"Remember when 'on water' matters were secret?" Mr Fitzgibbon told the Seven Network.

"The government would not talk about it, but when it is convenient, you get front-page photographs like we saw this morning."

Mr Dutton said he was always planning to release the details on Monday.

"You'll be criticised if you don't release it and criticised if you do," he told 3AW radio.

The minister said Sri Lankan asylum seekers were risking the sea journey due to deadly terror attacks in the country at Easter, as well as the Australian federal election in May.

"It is the reason Sri Lanka was the first country I visited after the election, to make sure we can keep these boats stopped. This threat is very real," Mr Dutton told The Courier-Mail.

News of last month's asylum seeker boat comes as a Tamil family being held on Christmas Island are waiting to find out if a court will allow them to stay in Australia.

An interim injunction blocking the deportation of Priya, her husband Nadesalingam and their Australian-born children Kopika, 4, and Tharunicaa, 2, has been extended until Wednesday.

Australian Associated Press