Under the 368.5 million euro deal signed in April between COSCO and Greece's privatisation agency, COSCO is to buy 51 percent of Piraeus for 280.5 million, with a further 16 percent for 88 million after a five year period. It is also contingent on completing investments worth 350 million euros over the next decade.

The sale of Greece's biggest port had been halted by the leftist government of Alexis Tsipras when it won elections in January last year but it was resumed under Greece's 86 billion-euro bailout deal agreed with its euro zone partners in August.

Privatisations are a major element of Greece's bailouts since 2010, but political foot-dragging and a highly unionised workforce in the public sector have been hurdles.

Cosco representatives in Greece objected strongly to terms of a first draft submitted to parliament on Wednesday, saying it clearly violated terms of the accord signed last April.

Greek officials scrambled on Thursday to fill in the gaps, while downplaying the fracas.

"The government, in concert with the privatisation fund, did what it ought to do and made the required improvements to be consistent with the endorsement law," Olga Gerovasili, the government spokeswoman, said in a statement.

(Reporting by Lefteris Papadimas; Editing by Dominic Evans)