A Philippine official says surveillance photographs have shown that China's land reclamation in contested reefs in the South China Sea has become "massive" with Beijing continuing its expansion in disputed territories despite protests.

Philippine Foreign Undersecretary Evan Garcia and the top U.S. diplomat in East Asia, Daniel Russel, said in a news conference in Manila Wednesday that their countries have separately urged Beijing to stop activities that could worsen tensions and violate a 2002 accord designed to prevent armed conflicts over contested islands and reefs.

Garcia said: "It is massive, just look at the photographs." He says China's activities are designed to change the status quo.

The photographs were not immediately distributed to the media.

Russel and Garcia say their governments will only back a peaceful resolution of the disputes.