The Philippine government's preferred name for the disputed waterway better known as the South China Sea was previously viewable only if specifically sought by name, according to AFP journalists who kept screenshots of earlier searches.

The name South China Sea remains visible to the north and west of the area newly identified as the West Philippine Sea.

Beijing claims the South China Sea almost in its entirety despite an international ruling that its assertion has no merit.

China has deployed navy and coast guard vessels in a bid to bar the Philippines from strategically important reefs and islands in the strategic waterway, leading to a string of confrontations in recent months.

Philippine armed forces spokeswoman Francel Margareth Padilla welcomed on Monday "the inclusion of 'West Philippine Sea' on Google Maps".

"As defenders of national sovereignty, the (military) sees this as a valuable contribution to truthful representation and public awareness," she said in a statement.

Then-Philippine president Benigno Aquino issued a directive in April 2012 calling for the sea's renaming as a standoff over the Scarborough Shoal was heating up between Beijing and Manila.

The administrative order said the renamed areas specifically included "the Luzon Sea as well as the waters around, within and adjacent to the Kalayaan Island Group and Bajo De Masinloc, also known as Scarborough Shoal".

AFP journalists who visited Google Maps last year discovered the name West Philippine Sea was visible only if searched by name but invisible to those who simply scrolled over the area otherwise.

It was not immediately clear what prompted Google to make the change.

Messages to Google, the Philippine Ministry of Foreign Affairs and the Chinese Embassy in Manila seeking comment were not immediately answered.