The United States led a group of regional countries in calling China’s actions during a dispute over the Panama Canal a “threat,” prompting backlash from Beijing on Wednesday.

Washington and Beijing accuse each other of seeking to control the Panama Canal, a vital trade link between the Atlantic and Pacific oceans.

Panama took control of two of the canal’s ports previously operated by a Hong Kong-based conglomerate following a decision by the Panamanian Supreme Court in January.

Since then, Washington has alleged China detained two Panama-flagged ships in response to the takeover, while China has threatened Panama with payback and rejected the US claims.

The United States led countries including Bolivia, Costa Rica, Guyana, Paraguay and Trinidad and Tobago on Tuesday in calling China’s actions “a blatant attempt to politicize maritime trade and infringe on the sovereignty of the nations of our hemisphere”.

“Panama is a pillar of our maritime trading system, and as such must remain free from any undue external pressure,” the US State Department said in the joint statement.

“Any attempts to undermine Panama’s sovereignty are a threat to us all.”

China’s foreign ministry slammed the statement as a “smear” on Wednesday.

“It is the United States that is politicizing and over-securitizing the port issue,” ministry spokesman Lin Jian told a news briefing.

“It is the United States that is hypocritically posturing and spreading rumors and smears everywhere.”

Trump returned to office last year vowing to seize back US control of the Panama Canal, which was handed over in a deal reached by former president Jimmy Carter, who vowed that the US would respect its sovereignty.

After Panama’s moves against the Hong Kong-based company, Trump declared victory and the canal issue largely disappeared as a point of contention between the countries.

In a national security strategy last year, the Trump administration vowed aggressively to promote US interests in Latin America against outside powers led by China.

A subsidiary of Hong Kong conglomerate CK Hutchison said on Tuesday it filed an arbitration against shipping giant Maersk, accusing the Danish group of seeking to replace its operations in the Panama Canal.

The Panama Ports Company said in a statement that Maersk broke a contract by siding with Panamanian authorities in a dispute over the waterway that saw a court annul in January the PPC’s rights to manage two key ports.

“Maersk undermined the contract and aligned with the Republic of Panama in connection with its State campaign against PPC and scheme to replace it through a takeover that installed new port operators,” the company said.

The arbitration will be held in London, PPC said, adding that the claim against Maersk is separate from “ongoing steps by PPC to hold Panama to account for its anti-contract and anti-investor conduct”.

The PPC said that since the takeover in January, a Maersk-affiliated port operator has utilised PPC facilities and information under a “pre-arranged concession contract” to manage the Balboa terminal.

Panama declared in February that a Maersk subsidiary, APM Terminals, would operate the port of Balboa, and that Terminal Investment Limited, owned by the logistics giant MSC, would manage the port of Cristobal.

The PPC filed a lawsuit opposing the suspension of its Panama Canal operations in February, and announced a month later it was seeking at least US$2 billion in damages.

Panama has been caught up in broader tensions between the United States and China, with President Donald Trump last year claiming, without evidence, that China effectively runs the canal.

The United States last week reiterated accusations that China had detained Panama-flagged ships in response to the takeover of the key ports — claims Beijing said were fabricated.

The Panama Canal, which connects the Atlantic and Pacific oceans, handles about 40 percent of US container traffic and five percent of world trade.