In a statement on Friday, the Hamburg-based International Tribunal for the Law of the Sea (ITLOS) said a TMC subsidiary had "initiated proceedings" against the International Seabed Authority (ISA) over alleged "breach of due process."

The subsidiary, Nauru Ocean Resources Inc (NORI), is asking the court to prevent the ISA from canceling its exploratory contract, which is up for renewal in July.

The dispute stems from TMC's move last year to seek regulatory approval from US President Donald Trump's business-friendly administration to begin operations in international waters.

The request was viewed as a bid to sidestep the Jamaica-based ISA, which has yet to finalize rules to govern the industry after years of protracted negotiations.

Deep-sea mining aims to plumb previously untouched seabeds for commodities including nickel, cobalt and copper, which are used in everything from rechargeable batteries to military technology.

Following TMC's application with US authorities, the ISA asked its technical committee to pay "specific attention to possible non-compliance" with respect to certain contracts.

TMC viewed the language as a veiled threat to its ISA-issued exploratory contract.

The ISA's identification of TMC's subsidiary as a contractor needing "specific attention" was "taken without lawful procedural basis and in breach of due process," TMC argues in its suit, according to the ITLOS statement.

Louisa Casson of Greenpeace International blasted the new suit as "corporate bullying" and urged ISA members to "stand strong against this attempted intimidation."

The United States is not party to the ISA or to the UN Convention on the Law of the Sea (UNCLOS), under which the authority was established in 1994.