QUITO (Reuters) - South American nations on Saturday rejected the U.S. decision to label Venezuela a security threat and sanction seven officials, lending President Nicolas Maduro regional support in the diplomatic dispute with Washington.

Foreign Ministers of the twelve-country Union of South American Nations (UNASUR) called for a revocation of the measures, which Maduro has blasted as an attempt to unseat him.

"It constitutes an interventionist threat to sovereignty and the principle of non-interference in the internal affairs of other countries," UNASUR said in a statement from Ecuadorian capital Quito.

The regional backing is further evidence the U.S. action against Venezuela has benefited Maduro, whose popularity has tumbled in hand with a severe economic recession.

"Long live the South American nation!," Maduro exclaimed in celebration on Saturday night, flanked by members of the military who had just led a defense exercise in the face of an alleged U.S. threat.

Venezuela's opposition says Maduro is amplifying the bilateral tensions to distract from shortages of everything from toilet paper to chicken, inflation of around 70 percent, and sky-high crime.

The leader has revved up his revolutionary rhetoric this week to rally supporters at home and around Latin America.

The region remains deeply scarred by Washington's backing of coups during the Cold War and is sensitive to any hints of meddling from the superpower to its north.

Maduro's adversaries, however, accuse fellow Latin American states of turning a blind eye to what they deem human rights violations and a crackdown on dissent in Venezuela.

(Reporting by Alexandra Valencia; Writing by Alexandra Ulmer; Editing by Marguerita Choy)