Located in the Spratly archipelago, the Second Thomas Shoal hosts a small detachment of Philippine forces aboard a grounded navy vessel and has been the site of clashes with Chinese ships.

Beijing claims almost the entirety of the crucial waterway despite an international ruling its assertion has no merit.

The US government's contracting website, Sam.gov, locates one of the proposed repair facilities in Palawan province's Quezon municipality.

The facilities "will provide repair and maintenance capabilities for a variety of (Philippine) vessels including 7.32-meter (24-foot) watercraft as well as other smaller conventional watercraft," the bid notice for the Quezon project reads.

The Philippines owns several vessels that size, including rigid-hull inflatable boats (RHIBs) that have been involved in clashes with larger Chinese ships.

While there are not believed to be existing permanent military facilities in Quezon, the area has hosted parts of joint US-Philippine military exercises for the past two years.

The US embassy in Manila confirmed on Wednesday the tender for both the Quezon project and a similar one to be constructed at the Philippines' existing Oyster Bay naval facility about 130 kilometres north.

Officials from the Philippine Department of Defense did not immediately provide comment.

Retired Philippine admiral Rommel Jude Ong, now a military analyst with the Ateneo de Manila University, told AFP such facilities could be used "for RHIBs, but more likely for smaller rubber boats used in the resupply of occupied features".

The Philippines and the United States have deepened their defence cooperation since President Ferdinand Marcos took office in 2022 and began pushing back on Beijing's sweeping South China Sea claims.