Several Chinese travel agencies have suspended tours to the Philippines, amid an escalating, month-long standoff over a group of uninhabited islands in the South China Sea.

The official Xinhua news agency said Thursday that China's largest online travel service company, Ctrip.com, and several other travel agencies suspended tours to the Philippines and will not accept bookings until the situation improves.

The standoff began on April 10 when Chinese surveillance ships prevented a Philippine warship from arresting Chinese fishermen in the contested waters near the Scarborough Shoal, which both sides claim as sovereign territory.

China's Foreign Ministry said earlier this week that it was not optimistic about solving the dispute and that it is ready to respond to “any escalation” by the Philippines.

Chinese state media on Thursday hinted at the possibility of war if the dispute is not resolved soon. An editorial in the official China Daily said Beijing prefers a peaceful solution, but insisted that Manila is “pressing us into a corner where there is no other option left but the use of arms.”

China says the islands, known as Huangyan in China, are a key part of Chinese territory and that any Philippine claim to them is baseless. The Philippines says the shoal is within its internationally recognized exclusive economic zone.

China has already rejected a request by the Philippines to refer the issue to an international court.

The standoff is part of a wider territorial dispute in the South China Sea, parts of which are also claimed by Vietnam, Taiwan, Malaysia, and Brunei. China claims nearly the entire region, which is thought to contain large amounts oil and natural gas.