WASHINGTON (UPDATE) - The United States on Wednesday laid out its most detailed case yet against Beijing's "unlawful" claims in the South China Sea, rejecting both the geographic and historic bases for its vast, divisive map.

In a 47-page research paper, the State Department's Bureau of Oceans and International Environmental and Scientific Affairs said China had no basis under international law for claims that have put Beijing on a collision course with the Philippines, Vietnam and other Southeast Asian nations.

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"The overall effect of these maritime claims is that the PRC unlawfully claims sovereignty or some form of exclusive jurisdiction over most of the South China Sea," the paper said, referring to the People's Republic of China.

"These claims gravely undermine the rule of law in the oceans and numerous universally recognized provisions of international law reflected in the Convention," it said, referring to a 1982 UN treaty on the law of the sea ratified by China -- but not the United States.

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Releasing the study, a State Department statement called again on Beijing "to cease its unlawful and coercive activities in the South China Sea."

The paper is an update of a 2014 study that similarly disputed the so-called "nine-dash line" that forms the basis for much of Beijing's stance.

In 2016, an international court sided with the Philippines in its complaints over China's claims. Beijing replied by offering new justifications, including saying that China had "historic rights" over the area.

• READ: Hague court's full ruling on Philippines vs. China

The State Department paper said that such historical-based claims had "no legal basis" and that China had not offered specifics.

It also took issue with geographic justifications for China's claims, saying that more than 100 features Beijing highlights in the South China Sea are submerged by water during high tide and therefore are "beyond the lawful limits of any state's territorial sea."

Beijing cites such geographic features to claim four "island groups," which the State Department study said did not meet criteria for baselines under the UN convention.

In response, China disputed the Americans' report, calling it a misrepresentation of international law designed to confuse and “upset the regional situation.”

"The media note and study of the US side misrepresent international law to mislead the public, confuse right with wrong and upset the regional situation,” Chinese Foreign Ministry spokesperson Wang Wenbin said in his regular press conference in Beijing on Thursday.

Wang said China, as a signatory, “earnestly observes” the United Nations Convention on the Law of the Sea (UNCLOS) “in a rigid and responsible manner” and claimed that the United States has refused to join the Convention.

“It wantonly misrepresents the Convention and adopts double-standards out of selfish gains. Such political manipulation is irresponsible and undermines international rule of law," he said.

“China enjoys historic rights in the South China Sea. Our sovereignty and relevant rights and interests in the South China Sea are established in the long course of history and are in line with the UN Charter, UNCLOS and other international law."

Wang also maintained China’s position rejecting the 2016 arbitral award to the Philippines, saying that it is “illegal, null and void.”

"China does not accept or recognize it,” he said.

The report was issued as the United States increasingly challenges China on the global stage, identifying the rising communist power as its chief long-term threat.

In 2020, then-secretary of state Mike Pompeo explicitly backed claims of Southeast Asian nations in the South China Sea, going beyond the past US stance of challenging China without taking an issue on which countries were right.

The South China Sea is home to valuable oil and gas deposits and shipping lanes, and Beijing's neighbors have frequently voiced concern that their giant neighbor was seeking to expand its reach.

— With a report from Willard Cheng, ABS-CBN News

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