Twenty asylum seekers from Sri Lanka tried to reach Christmas Island last week but were intercepted and flown back to Colombo.

Mr Dutton says the boat left in early May and people smugglers were trying to test the re-elected government's resolve.

"I think they were in the process of doing exactly that on this occasion," he told 2GB radio on Thursday.

"We need to make sure that people hear the very clear message that if you attempt to come here by boat, you won't come to this country, and the settings under the Morrison government will not be softened."

Mr Dutton said it was a "very dangerous period" for boat arrivals, hinting that "it's not the only vessel we're worried about".

The minister has urged Labor to abandon its support for the so-called medevac laws, which make it easier for sick asylum seekers being held offshore to seek medical transfers.

"The government is going to repeal the medevac bill if we're able to get the numbers in parliament - so we need the Labor Party for that," he said.

"That is also a green light for people to come to our country from Manus Island and Nauru, and again, that would send the wrong signal to people smugglers who are marketing Australia as an outcome."

Mr Dutton says Opposition Leader Anthony Albanese will be given a security briefing on the latest boat arrival, as is customary.

"We'll be happy to give him a briefing, but frankly we've given briefings to every Labor shadow minister and leader of the opposition for many years," he told Sky News.

"They just don't listen to the advice, that's the problem."

Mr Albanese pointed out 10 asylum seeker boats had arrived from Sri Lanka since 2013 under the coalition government's watch.

The latest boat left Sri Lanka in the first week of May, not long after the deadly Easter bombing attacks on hotels and churches.

Mr Dutton said the government had a mandate for strong border protection policies, following the election win.

Australian Associated Press