Immigration Minister Peter Dutton believes people smugglers are monitoring every word he says about government efforts to stop asylum-seeker boats.
He has declined to comment on reports a vessel was sighted off the West Australian coast this week, saying his refusal was consistent with past practice and part of the reason why the government had been able to stop the boats.
"The sophistication of the people smuggling network, they are monitoring every word that I say ... in relation to the boats," he told Sky News on Wednesday.
Mr Dutton hinted the passengers aboard the boat might be returned to Vietnam, acknowledging there was good bilateral relationships the country.
"Where if it is safe to do so and we've met our international obligations, we don't owe people protection, those people will go back to their country of origin," he told reporters in Sydney.
"Just because somebody is on a boat does not make them a refugee."
