BEIJING, Oct 14 (Reuters) - China has taken

countermeasures against five U.S.-linked subsidiaries of South

Korean shipbuilding firm Hanwha Ocean, the Chinese

commerce ministry said on Tuesday.

Organisations and individuals within China are prohibited

from engaging in any transactions, cooperation or related

activities with these entities, the ministry said in a

statement.

"Hanwha Ocean's U.S.-related subsidiaries have assisted and

supported the U.S. government's relevant investigative

activities, thereby jeopardising China's sovereignty, security,

and developmental interests," the statement said.

Hanwha did not immediately respond to a Reuters request

for comment.

The move comes on the day that China and the U.S. implement

additional port fees targeting each others' vessels, although

China has exempted ships it built.

U.S. President

Donald Trump

's administration announced earlier this year plans to levy

fees on China-linked ships to loosen Beijing's grip on the

global maritime industry and bolster U.S. shipbuilding.

China hit back last week saying it would impose its own

port fees on U.S.-linked vessels on the same day then U.S. fees

come into effect.

China has called U.S. measures targeting its maritime,

logistics, and shipbuilding industries a serious violation of

international law and fundamental norms of international

relations.