By Kirsty Needham

SYDNEY (Reuters) -Australia plans to significantly boost surveillance of Pacific Islands territorial waters, spending A$477 million ($310.72 million) on aerial patrols for illegal fishing fleets, tender documents viewed by Reuters show, as China takes steps towards sending its coast guard to the region.

Australia's Prime Minister Anthony Albanese will visit Fiji on Friday, the Fiji Times newspaper reported, after the government of Prime Minister Sitiveni Rabuka last week approved a maritime security agreement that will see Australia fund a patrol boat for Fiji.

Australia will operate commercial aerial patrols to support Pacific Island countries monitoring exclusive economic zones which span millions of kilometres of ocean. Efforts to tackle illegal fishing also led to a new monitoring centre being opened in Fiji in April.

Australia's defence department declined to comment on the aerial tender, and Pacific Minister Pat Conroy did not respond to a request for comment.

Reuters reported last week that China's coast guard is taking further steps towards high seas boarding of fishing boats in the Pacific for the first time, risking tensions with Taiwanese fleets that also ply the region.

The Chinese Coast Guard demonstrated the capabilities of one of its largest ships, used to enforce maritime law in the Taiwan Strait, to 10 Pacific Island ministers, including Fiji's, in China a fortnight ago.

China has registered 26 coast guard vessels for Pacific Ocean patrols with the Western and Central Pacific Fisheries Commission, although it is yet to conduct an inspection, WCPFC officials said. China declined to comment.

Australia has gifted two dozen patrol boats to Pacific Island nations, and operates navy and air force patrols for illegal fishing in the region several times a year.

Sangaa Clark, chief executive of the Parties to the Nauru Agreement, representing nine Pacific Island countries controlling the world's largest tuna fishery, said the group has not invited China to conduct coast guard patrols, and instead relied on Australian-funded surveillance and patrols by Australia, New Zealand, France and the United States.

Pacific security expert Peter Connolly, a fellow at the University of New South Wales, said Chinese Coast Guard patrols in the region would "introduce geostrategic tensions to the policing of the Pacific's fisheries".

"This is particularly likely because the two most common nationalities of illegal fishermen in the Pacific have been from the PRC and from Taiwan," he said, referring to the People's Republic of China.

($1 = 1.5352 Australian dollars)

(Reporting by Kirsty Needham in Sydney, editing by Ed Osmond)