MOSCOW (Reuters) - A foreign policy adviser to U.S. Republican candidate Donald Trump has accused Washington of contributing to an atmosphere of mutual contempt with Moscow by disregarding Russia's interests.

Carter Page, a former investment banker whose views on Russia have caused controversy in the past, made the comments in an opinion piece for Russia's state-controlled Sputnik news agency that was published on Thursday.

"From Syria to Ukraine to world energy policy, Russia remains an essential piece in the puzzle for solving many of Washington's most pressing geostrategic challenges," Page wrote in the article.

The U.S. government had shown a "complete disregard for Russia's interests", Page said, saying this had fueled a sharp deterioration in bilateral relations.

Trump, the Republican nominee for next month's U.S. election, named Page as being among five foreign policy advisers in March. Both Trump and Page are known for their more conciliatory stance toward Russia, in contrast to the views of many prominent Republicans.

In a speech in Moscow in July, Page criticized Western countries for what he said was their "hypocritical focus on democratization" in the post-Soviet world.

(Reporting by Alexander Winning; Editing by Andrew Osborn)