Australia will fund new undersea telecommunications cables for Solomon Islands, provide a $600 million bailout for Papua New Guinea and spend $400 million to expand diplomatic posts in the Pacific in the contest with China for regional influence.

In the budget announced on Tuesday, the Department of Foreign Affairs will also get $188 million to upgrade communications and security to protect its Canberra headquarters and network of foreign posts from cyber threats, and $40 million more over two years to urgently carry out repairs and renovations at embassies.