Tourists companies such as Ctrip.com, China's largest online travel service company, and Beijing Caissa International Travel Service Co. Ltd., have halted travel tours to the Philippines and promised to refund tourists that have signed for tours to the country.

　　The dispute over Huangyan Island unfolded after the Philippines recently sent a warship to harass 12 Chinese fishing vessels which sailed into the island's waters to shelter from bad weather.

　　The travel agencies said they will watch the development of the situation, and adopt precautionary measures to ensure safety of their clients currently traveling in the Philippines.

　　China's Vice Foreign Minister Fu Ying said Tuesday that China is not optimistic about the Huangyan Island situation, and is fully prepared to respond to anything the Philippine side does to escalate the dispute.