SEOGUIPO, South Korea, Jan. 31 (Yonhap) -- The Navy began taking measures Saturday to drive sit-in protesters out of the construction site of a naval base on a major southern island to complete the construction project by December as planned, triggering strong resistance from the protesters. Civic groups, environmental activists and some residents in the village near the construction site have staged protests in a make-shift tent at the entrance of the site since October last year when the Navy began constructing apartment buildings to be used as an official residence for military officers to work at the naval base. About 1,000 officials, including some 800 police officers, were in place at the scene to eject the protesters. "We're going to remove vehicles and a protest tent illegally built to interfere with the construction from the site," said a military official sent to carry out the administrative action. The action immediately caused a fierce physical clash between police officers and the residents of Gangjeong village and their supporters. The Navy said they had no other option but to drive them out in order to complete the construction of five four-story apartment buildings that would house essential members of navy operations and their families in the future, timed with the completion of the naval base in December as planned. The military has been constructing a modern military port that would hold up to 20 warships simultaneously, along with two 150,000 ton cruise ships. The military says the Jeju base, if completed as scheduled in December, will give Seoul a launching point for sending naval vessels into the South Sea, a key trade route for South Korea. But the opponents have long staged protests and taken legal steps to halt construction, citing potential environmental damage to the area designated as a UNESCO Biosphere Reserve.