Prime Minister Tony Abbott has described Australia's measures to stop asylum seekers arriving by boat as tough but effective, saying 50 days had passed since any asylum seeker had reached Australia by boat, the longest period since 2008.

His comments come as the Australian Broadcasting Corp. reported that the Australian navy had sent 34 asylum seekers who attempted to reach Australia aboard a rickety Indonesian boat back to the main Indonesian island of Java on Wednesday in an enclosed lifeboat.

The government on Friday maintained its five-month-old policy of refusing to say whether it had ever turned back asylum seekers who attempt to reach Australian shores on boats from Indonesia.