Adds Chinese embassy comment in paragraphs 7-8

WASHINGTON, Feb 26 (Reuters) - The United States imposed sanctions on six entities based in Hong Kong and China on Wednesday that it accused of being involved in an Iranian drone procurement network, as the Trump administration implements its "maximum pressure" campaign against Tehran.

The U.S. Treasury Department said the entities engaged in the procurement of unmanned aerial vehicle $(UAV.UK)$ components on behalf of an Iranian firm under U.S. sanctions, Pishtazan Kavosh Gostar Boshra, and its subsidiary Narin Sepehr Mobin Isatis, adding that the firms were key suppliers of Iran's UAV and ballistic missile programs.

Reuters could not immediately reach PKGB or NSMI for comment.

"Iran continues to try to find new ways to procure the key components it needs to bolster its UAV weapons program through new front companies and third-country suppliers," Treasury Secretary Scott Bessent said in a statement.

"Treasury remains committed to disrupting the schemes that enable Iran to send its deadly weapons abroad to its terrorist proxies and other destabilizing actors."

Iran's mission to the United Nations in New York did not immediately respond to a request for comment.

Liu Pengyu, spokesperson for China's embassy in Washington, said China and Iran's cooperation was "reasonable and legal".

"China has always firmly opposed the illegal unilateral sanctions imposed by the United States and will firmly safeguard the legitimate rights and interests of its enterprises and citizens," he said.

The action comes after the United States on Monday imposed a fresh round of sanctions targeting Iran's oil industry, the Islamic Republic's main source of income.

The announcements come as U.S. President Donald Trump seeks to bring Iran's crude exports to zero to prevent the country from obtaining a nuclear weapon, and builds on the layers of sanctions already imposed by his government and the previous Biden administration.

Trump earlier this month had restored his "maximum pressure" campaign on Iran that includes efforts to drive the country's oil exports to zero, reimposing Washington's tough policy on Iran that was practiced throughout Trump's first term.

The Islamic Republic's top diplomat said on Tuesday that Iran would not succumb to pressure and sanctions imposed by Washington.

Wednesday's action freezes any U.S. assets of those targeted and generally bars Americans from dealing with them.

(Reporting by Daphne Psaledakis and Caitlin Webber; Additional reporting by Michael Martina; editing by Philippa Fletcher, Alexandra Hudson)

((caitlin.webber@thomsonreuters.com;))