Japanese Prime Minister Shinzo Abe has claimed victory in an election for the upper house of parliament, saying voters backed his economic policies.

Exit polls suggest his coalition will win most of the 121 seats in contention, increasing its majority.

If he secures a two-thirds majority to match that in the lower house, he could hold a vote on constitutional change, easing constraints on military action.

But Mr Abe says it is too early to talk about this controversial review.

Half of the 242 seats of the upper house were up for grabs.