An Australian billionaire businessman has announced his minor party has struck a vote-swap deal with the ruling party that improves the government's chances of being re-elected in a general election on May 18.

Clive Palmer announced the deal with Prime Minister Scott Morrison's conservative Liberal Party as early voting began Monday in the election, in which the ruling coalition is seeking a third three-year term.

Palmer told reporters that the center-left opposition Labor Party also wanted to strike a deal with the party he created, United Australia Party, but were refused because "their policies would destroy Australia."

Labor denies seeking such a deal.

Under Australia's system, voters rank candidates in order of preference. Those ranked highest by a majority of voters have a better chance of being elected.