By Jonathan Saul, Yannis Souliotis and Renee Maltezou

ATHENS/LONDON (Reuters) - Greece's biggest port Piraeus is operating normally following a U.S. blacklisting this week of its majority owner, China's largest shipping group COSCO, while the Greek government is examining its potential impact, sources told Reuters on Friday.

The U.S. Defense Department said on Monday it had added COSCO Shipping to a list of companies it said worked with China's military, which the shipping industry sees as a step aimed at deterring U.S. companies from trading with the Chinese company.

COSCO, one of the world's largest shipping groups, said on Wednesday that none of its units on the list are military companies, that its global operations continued uninterrupted, and that it would clarify the issue with U.S. authorities.

The U.S. blacklisting does not have the weight of a legal sanction for the commercial sector, but it has alarmed Greece where Piraeus, one of the largest ports in the Mediterranean in terms of throughput, has already experienced a drop in trade as a result of the Red Sea crisis, where Yemen's Houthis have been attacking commercial shipping.

"I don't see an impact on Piraeus, but it is still early," a Greek official with knowledge of the matter said.

Greece is monitoring the situation and has discussed the issue with other EU counterparts, a second Greek official said. A COSCO subsidiary operates terminals also in Spain and Italy.

"There is potential for 'self-sanctioning' on the part of market players out of fear of running afoul of U.S. policy," said Jefferies analyst Omar Nokta.

Ulf Bergman, senior economist with freight platform Shipfix, said while the blacklisting did not involve any legal sanctions, it might act as a deterrence for many importers.

A Greek shipowner, who spoke on condition of anonymity, said the blacklisting was a move in a power game between China and the U.S. rather than a game changer.

Danish shipping group NORDEN told Reuters that the ruling had not affected its business so far.

"We are constantly monitoring developments and will adjust accordingly," it said.

In 2019, the U.S. imposed sanctions on two COSCO subsidiaries, which prompted shipping companies to briefly suspend chartering their vessels until the sanctions were lifted.

(Reporting by Renee Maltezou, Jonathan Saul and Yannis Souliotis. Editing by Jane Merriman)