Chinese coast guard vessels prevented a Philippine nationalist group from planting a Filipino flag on a rocky South China Sea outcrop, the group said Monday, the latest territorial standoff between the two countries.

The incident between the coast guard and the Kalayaan Atin Ito (Freedom It's Ours) group took place at the disputed Scarborough Shoal on Sunday, just as foreign ministers from Southeast Asian countries and China prepared for a meeting in Kunming to discuss territorial rows in the hotly contested waters.

Beijing claims almost the entire South China Sea and the move by the Filipino nationalists comes as the Permanent Court of Arbitration in the Hague prepares to deliver a ruling on a complex case brought by Manila that could dent China's sweeping sovereignty claim.