The firm said in March it was offloading the firms -- including operations in the vital Central American waterway -- to a group led by asset manager BlackRock for $19 billion in cash.

The sale was seen as a political victory for US President Donald Trump, who had vowed to "take back" the Panama Canal from alleged Chinese control, prompting Beijing's ire.

China's market regulator said in March it was reviewing the deal.

"(CK Hutchison) remains in discussions with members of the consortium with a view to inviting (a) major strategic investor from (China) to join as a significant member of the consortium," CK Hutchison said in a stock exchange filing Monday.

The firm added that changes to the consortium's membership and deal structure will be needed for the deal "to be capable of being approved by all relevant authorities".

It added that the "period for exclusive negotiations" mentioned in the March announcement had expired, but that discussions will continue.

It did not name the major investor.

China's biggest shipping company Cosco was set to join the consortium and was requesting veto rights or equivalent powers, Bloomberg News reported.

Bloomberg Intelligence analyst Denise Wong told the outlet that "ongoing negotiations and the reported inclusion of Cosco Shipping in the consortium have likely eased concerns over Chinese regulatory hurdles, strengthening investor confidence in the deal's viability".

CK Hutchison said it "intends to allow such time as is required for such discussions to achieve" a workable arrangement.

It said it had stated on several occasions that it "will not proceed with any transaction that does not have the approval of all relevant authorities".

Its Hong Kong-listed shares climbed nearly one percent Monday, while Cosco rose 0.5 percent.

The consortium's original structure was designed to pass control of CK Hutchison's two Panama ports to BlackRock's Global Infrastructure Partners unit, while the remaining ports will go to Italian billionaire Gianluigi Aponte's Terminal Investment Limited.

AFP has contacted Cosco for comment.

The Panama Ports Company, a CK Hutchison subsidiary, has managed the port of Cristobal on the canal's Atlantic side and Balboa on the Pacific side since 1997, via a concession from the Panama government.

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BLACKROCK

COSCO