Hapag-Lloyd and CMA CGM said they would comply with the US Federal Maritime Commission (FMC) probe into congestion fees that liner operators have begun charging shippers.
The FMC announced on Wednesday last week that it was requesting documentation from eight companies to see if new fees charged ostensibly due to congestion were implemented properly.
The other six liners targeted are HMM, Matson, Mediterranean Shipping Co, Orient Overseas Container Line, SM Line and Zim.
Announcing the new probe, FMC chairman Daniel Maffei said the agency had been hearing about new, unexpected fees being charged by liners.
"It seems to me that these factors would already have been included into the record-high rates charged by the carriers," he said in a statement.
Tasked with regulating shipping in accordance with the US Shipping Act, the watchdog has launched several initiatives following the 9 July executive order from President Joe Biden on competitiveness in the US economy.
The eight companies called upon to answer to the FMC differ from the nine the watchdog announced in July that it would be auditing for detention and demurrage practices.
MSC, CMA CGM, Hapag-Lloyd and HMM are involved in both, with AP Moller Maersk, Cosco, Ocean Network Express, Evergreen and Yang Ming also included in the audit.
In a statement to TradeWinds, Hapag-Lloyd said the current sky-high freight rates were the result of "exceptionally strong demand" from the US, plus from infrastructure bottlenecks across the supply chain.
"We are doing everything in our power to cope with this strong demand, to provide additional transport capacity and to meet the needs of our customers," the company said.
"At the same time, these inefficiencies cause additional costs and remain a burden for all market participants, including the carriers.
The German company said it always complies "with filing requirements as defined by relevant authorities".
In a much shorter statement, French giant CMA CGM said it is fully complying with the FMC "and will provide them with all relevant information".
The liners have until 13 August to turn over documentation.
In addition to the audit and the congestion fee investigation, the FMC has also asked for more enforcement power, changes to laws making it easier for shippers to bring complaints against liners and executed a memorandum of understanding with the Department of Justice's antitrust division.
