WASHINGTON, March 18 (Reuters) – The United States on Wednesday identified seven companies that it has blacklisted for trade in Iranian petrochemicals – three based in mainland China, three in Hong Kong and one in South Africa – the State Department said in a statement.

Separately, the department also named five Iranian nuclear scientists who the Commerce Department said it sanctioned on Tuesday for having taken part in Iran’s pre-2004 nuclear weapons program and who continue to be employed by the Iranian state.

The Trump administration on Tuesday had said it would blacklist the seven companies and five individuals but did not name them.

The announcements appeared designed to signal Washington would not ease its campaign of choking off Tehran’s ability to export its oil, despite appeals from China and others that it do so on humanitarian grounds because of the coronavirus outbreak.

The U.S. “maximum pressure” campaign, instituted after Trump in 2018 unilaterally withdrew from the 2015 nuclear deal Iran struck with six major world powers, aims to force Tehran to limit its nuclear, missile and regional activities.

The State Department identified the firms targeted as Hong Kong-based Mcfly Plastic Hk Ltd, Saturn Oasis Co, Sea Charming Shipping Company Ltd; Chinese companies Dalian Golden Sun Import & Export Co. Ltd., Tianyi International (Dalian) Co. Ltd. and Aoxing Ship Management (Shanghai) Ltd. and South Africa’s SPI International Proprietary Ltd.

It also said it had targeted two entities which own or control SPI International and had knowledge of its sanctionable activities: South African company Main Street 1095 and Iranian entity Armed Forces Social Security Investment Company.

Further, the agency targeted Mohammad Hassan Toulai, managing director of Iran‘s Armed Forces Social Security Investment Company; Hossein Tavakkoli, director of SPI International; and Reza Ebadzadeh Semnani, director of Main Street 1095.

All of these entities and individuals were added to the U.S. Treasury Department’s Specially Designated Nationals list, blocking their assets under U.S. jurisdiction and generally barring U.S. persons from dealing with them.

The department also named five Iranian nuclear scientists who were added to the Department of Commerce’s Entity List as Aref Bali Lashak, Sayyed Mohammad Mehdi Hadavi, Kamran Daneshjou, Mehdi Teranchi and Ali Mehdipour Omrani.

Presence on the Entity List means the foreign parties are barred from receiving some or all items subject to U.S. export regulations unless the exporter secures a license, according to the department.

(Reporting by Susan Heavey and Arshad Mohammed; Editing by Chizu Nomiyama, Bernadette Baum and Paul Simao)