PNG should have known of posting: DFAT

The secretary of the foreign affairs department has conceded there was "miscommunication" with Papua New Guinea over a planned Australian diplomatic mission in Bougainville.

PNG prime minister Peter O'Neill was shocked by the May budget announcement, saying he hadn't been consulted by Canberra.

Department secretary Peter Varghese told a Senate committee in Canberra on Wednesday the plan should have been conveyed to Mr O'Neill and his foreign minister, but "regrettably" neither could be reached.