Venezuela's relations with the U.S. are frozen and President Hugo Chavez's government sees no possibility of improving them after its state oil company was hit with sanctions by Washington, the country's top diplomat said Sunday, according to AP. Foreign Minister Nicolas Maduro said Venezuela had been trying to establish a dialogue with U.S. officials since Barack Obama assumed the presidency after George W. Bush, but those attempts were spurned. «We've made every effort to establish a relationship of fluid communications,» Maduro said. «It's been impossible.» Tensions between the two countries reached their highest point while Bush was in office. Chavez expressed hope that would change when Obama became president, but he's repeatedly lamented that improving relations has not been possible. Maduro said he did not foresee any breakthrough in the strained ties with Washington, noting that relations have been particularly tense since the State Department slapped sanctions on Petroleos de Venezuela, or PDVSA, last month. «There's no indication that communication could be initiated,» Maduro said during an interview broadcast on the local Televen television channel. The U.S. imposed sanctions on PDVSA and six companies from other countries for doing business with Iran that helps finance the Iranian nuclear program. The State Department said PDVSA delivered at least two cargoes of refined petroleum products worth about $50 million to Iran between December and March. Venezuela's close ties with Iran have raised concerns among officials in Washington, who believe Iran is trying to build nuclear weapons. Iran says its program is meant only to generate electricity using nuclear reactors. Chavez has persistently defended Iran's nuclear energy program, saying it is for peaceful uses. The U.S. and Venezuela have been without ambassadors in each other's capitals since July 2010, when U.S. envoy Patrick Duddy finished his assignment and left Caracas. Chavez later rejected Obama's nominee for ambassador, Larry Palmer, accusing him of making disrespectful remarks about Venezuela's government. That led Washington to revoke the visa of the Venezuelan ambassador. Under the U.S. sanctions, PDVSA is barred from any U.S. government contracts, from U.S. taxpayer-subsidized import-export financing and from export licenses for sensitive technology. But PDVSA can continue selling oil to the United States or dealing with its U.S. subsidiaries. Energy Minister Rafael Ramirez has hinted PDVSA could seek to accelerate efforts to reduce its dependence on sales to the United States by exporting more heavy crude oil to China and other countries. Venezuela is one of the United States' main suppliers of petroleum, and the U.S. is the South American country's chief oil buyer. The U.S. also imposed penalties on Venezuela's Military Industries Co. for violating the Iran, North Korea and Syria Nonproliferation Act by selling or buying sensitive equipment and technology related to nuclear, chemical and biological weapons and ballistic missile systems.