But Dr Marinaccio said China blocked the credentials of three Taiwanese participants on Tuvalu's delegation list.
The Foreign Minister made a decision to return and will land in Brisbane on Monday nighttime instead of Lisbon.
The UN Oceans Conference is hosted by the governments of Kenya and Portugal and around two dozen heads of state and governments are expected to attend the event taking place from 27 June to 1 July.
Representatives from 193 countries will also be joining the conference, including 938 civil society groups, 75 foundations, and 74 universities.
