UPDATE 1-Unipec replaces ship charters after U.S. sanctions COSCO tanker units -sources

units -sources@ (Updates with details, background)

SINGAPORE/LONDON, Sept 26 (Reuters) - China's Unipec has made replacement bookings for four oil shipments from the Middle East Gulf after the United States imposed sanctions on the tanker subsidiaries of China's COSCO, three shipping sources said on Thursday.

The sources said Unipec, the trading arm of Asia's top oil refiner Sinopec, had switched to other tanker owners including China Merchants-owned AMCL after the designation by Washington on Wednesday of two of state-owned COSCO's subsidiaries.

Sinopec declined to comment. AMCL's Hong Kong office could not be reached for comment after office hours. An AMCL executive reached by Reuters declined to comment.

One of the sources said Unipec could seek to book further cargoes from the Middle East Gulf using AMCL's tankers.

The U.S. Treasury Department said on Wednesday it was imposing sanctions on five Chinese nationals and six entities that it said had violated Washington's unilateral curbs on Iran.

These included two COSCO Shipping Corporation subsidiaries, COSCO Shipping Tanker Dalian and COSCO Shipping Tanker (Dalian) Seaman and Ship Management Co Ltd, as well as a separate company Kunlun Shipping Company Limited. Beijing accused the United States of "bullying".

Indian Oil Corp said separately on Thursday it was examining the impact of the U.S. sanctions on its chartering of a tanker owned by one of the designated COSCO subsidiaries. (Reporting by Jonathan Saul and Chen Aizhu, Editing by Jan Harvey and Susan Fenton)