Reports that China has moved weapons to tiny islands in the South China Sea have angered local officials who fear the move could cause disruptions on some of Australia’s busiest trade routes, Fairfax has reported.

The report claimed Australian pilots and sailors could be sent on missions through the Spratly Islands region, which China is exerting control over, to demonstrate the right to freedom of navigation.

It is believed small islands in the region are being enlarged to bear Chinese airbases.

The area of reef that has been reclaimed by sand dredging could host long-range radar, anti-aircraft guns and regular surveillance flights, the report states.

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Defence agencies are upgrading the strategic threat assessments of the islands and suggested a regional operation to fly planes and sail ships through the contested area would show they do not recognise China’s claims.

China has said that its intentions are to use the land for fishing, search and rescue, “navigational safety”, environmental and humanitarian causes.

But in an opinion piece for the West Australian, China’s ambassador to Australia Ma Zhaoxu said the area around the islands would eventually be defended.

“It is China’s long-standing position that it has indisputable sovereignty over the South China Sea Islands and their adjacent waters,” Mr Ma said.

“After the construction, the islands and reefs will be able to provide all-round and comprehensive services to meet various civilian demands besides satisfying the need for necessary defence purposes.”

Defence chiefs are reportedly due to brief the Prime Minister Tony Abbott about the changes in the next fortnight.

Forbes Magazine published a report airing concerns the Chinese move could damage trade along the world’s busiest shipping lane, which moves billions of dollars worth of oil and liquefied natural gas.

“Control this flow and you control the energy security of Asia,” Forbes reported.

But Mr Ma said those concerns would not be realised.

“[China’s] efforts to uphold sovereignty and maritime rights in the South China Sea have not affected and will not affect freedom of navigation in that part of the sea in any way,” he said.

Despite his assurances, a US reconnaissance plane flew past the islands earlier this month within visual range and were warned to leave by the Chinese navy.

The contested islands are about 600 kilometres off the coast of China, but about 150km from the Phillipines.

AAP reported Opposition Foreign Affairs spokeswoman Tanya Plibersek warned countries work towards a resolution, ensuring the contested area remains open for shipping and any disagreements about sovereignty are worked through.