Vietnam on Thursday called for the “immediate withdrawal” of a Chinese ship in the South China Sea , as the stand-off over the disputed waters intensified. Beijing last week issued a new call for Hanoi to respect its claims to the resource-rich region – which has historically been contested by Vietnam , as well as Taiwan, the Philippines, Malaysia and Brunei. Hanoi responded by saying it had sent several messages to Beijing insisting that a Chinese survey ship vacate its waters, and doubled down on Thursday with new demands for the vessel’s removal. “Vietnam has had several appropriate diplomatic exchanges … requesting immediate withdrawal from Vietnam’s exclusive economic zone,” a foreign ministry spokesperson told reporters, while refusing to disclose the ship’s precise location. “Vietnam resolutely and persistently protects our sovereign rights … by peaceful means on the basis of international laws,” Le Thi Thu Hang added. The ship, owned by the government-run China Geological Survey, begun research around the contested Spratly Islands on July 3, according to the US-based Center for Strategic and International Studies (CSIS). Before it was spotted, a Chinese coastguard vessel also patrolled near Vietnamese supply ships in a “threatening manner”, CSIS said. China has not confirmed the presence of its ships in the area. China’s neighbours boost coastguards as tensions rise in South China Sea Beijing invokes its so-called nine-dash line to justify its claim to historic rights to the waterway, and has previously built up artificial islands as well as installed airstrips and military equipment in the region. The line runs as far as 2,000km (1,240 miles) from the Chinese mainland to within a few hundred kilometres of the Philippines, Malaysia and Vietnam. In 2014 Beijing moved an oil rig into waters claimed by Hanoi, sparking deadly anti-China protests across Vietnam. The latest stand-off in the sea prompted a swift rebuke from the United States over the weekend, calling for an end to China’s “bullying behaviour”. US accuses China of acting like a bully in the South China Sea “China’s repeated provocative actions aimed at the offshore oil and gas development of other claimant states threaten regional energy security,” the US State Department said Saturday. The US has long called for freedom of navigation in the South China Sea, and on Thursday said it sailed a warship through the Taiwan Strait .