China is refusing to budge over the country's claims to virtually all the South China Sea, saying it will not permit other nations to infringe on what it considers its sovereign rights in the strategically vital area.

Foreign minister Wang Yi, speaking to reporters at an annual news conference in Beijing, said another nation's claim to freedom of navigation in the region did not give it the right to do whatever it wanted - an apparent reference to the US, which has sent naval ships past reefs where China has engaged in island building.

Mr Wang sought to deflect allegations China was militarising the region by building armed forces facilities on the artificial islands. He said China's development there was defensive and other nations were being militaristic.

"China cannot be labelled as the most militaristic. This label is more suited to other countries," he said.

In addition to reaffirming that South China Sea islands were an "integral" part of China's territory that "every Chinese is obligated to defend", he reiterated Beijing's refusal to co-operate with an International Court of Arbitration case brought by the Philippines over disputed claims in the area.

China has conducted a massive program in the South China Sea over the past two years of land reclamation, piling sand atop reefs, then adding airstrips and military facilities.

Neighbours have complained that the work has raised tensions by changing the status quo in the area, where six Asian governments have overlapping claims and which include some of the world's busiest sea lanes.

When asked whether China would allow foreign journalists to visit those islands, Mr Wang stressed that they also were intended for civilian uses and once completed, foreign journalists would be invited.