The images, published by IHS Jane’s Defence Weekly, show construction work on reclaimed land on Fiery Cross Reef in the Spratly Islands.
The landmass could accommodate a runway about 3,000m long, the report said.
China’s land reclamation work in the area has raised concern around the Asia-Pacific region.
China claims almost the whole of the South China Sea, resulting in overlapping claims with several other Asian nations including Vietnam and the Philippines.
They accuse China of illegally reclaiming land in contested areas to create artificial islands with facilities that could potentially be for military use.
Images have emerged of work in multiple areas in the disputed Spratly islands. China says its work is legal and needed to safeguard its sovereignty.
Read more: http://www.bbc.com/news/world-asia-32331964