Asylum seekers who are believed to have destroyed their documents before arriving in Australia will have a presumption against refugee status under a coalition government, Opposition leader Tony Abbott says.

As part of three policy "enhancements", which the opposition leader said would immediately be put in place under a coalition government, Mr Abbott said there would be a "strong presumption that illegal boat people who have destroyed their documents not be given refugee status".

Tony Abbott: 90 per cent of people who arrive illegally via boat are currently being given successful outcomes. Credit:Penny Bradfield

Mr Abbott said his government would also ensure that his Immigration Minister "exercise the right" to appeal against affirmative decisions.

"This right has never been exercised under this government," he told reporters on Saturday.