Iranian oil offers to Chinese buyers fall as US blockade bites, sources say

By Siyi Liu and Chen Aizhu SINGAPORE, Aug 21 (Reuters) - Offers of Iranian crude to Chinese buyers have declined and prices have jumped this week as the U.S. blockade has cut Tehran's shipments, according to trade sources, with the threat of more sanctions from Washington looming. The U.S. re-imposed its blockade of Iran's shipping and ports on July 13 as a deal to halt the war between them broke down in an attempt to cut off oil sales — Tehran's primary source of hard currency — compounding…