In April, Chinese ports detained 136 merchant vessels flying the Panamanian flag, up from 93 in March, as reported by the UK-based security and analysis firm Ambrey.

The step-change followed months in which detentions had typically ranged between 13 and 32 per month from January of last year to February of this year.

Ambrey’s analysis said the March–April spike confirmed earlier reporting that Panama-flagged ships were being singled out when operating in Chinese waters.

It also stated that no similar rise had been recorded for any other major flag over the same period.

The firm's analysis added that the surge has continued since 8 March 2026 and has been presented as port state control activity. Ambrey reported “verbal instructions” from Chinese authorities to intensify inspections of Panama-registered tonnage in March.

The pattern is linked to developments around Panama Canal terminal concessions held by Hong Kong-based CK Hutchison. The reporting cited a Panamanian Supreme Court ruling that removed CK Hutchison’s concession over two terminals.

Soon after, the terminals were temporarily transferred to MSC and to Maersk’s port operator APM Terminals.

In response, China reportedly instructed Maersk and MSC last month to cease operating the Balboa and Cristobal terminals on the Panama Canal.

The directive included a warning against activities deemed harmful to Chinese interests and called on the companies to adhere to commercial ethics and international rules.

Despite this instruction, operations at both terminals are continuing under temporary arrangements approved by Panama.