The White House on Wednesday dismissed a blog post by an award-winning US political writer claiming the US was behind explosions of the Nord Stream gas pipelines as "utterly false and complete fiction".
Reuters has not confirmed the report, published by US investigative journalist Seymour Hersh, which said an attack was carried out last September at the direction of President Joe Biden.
"This is utterly false and complete fiction," said Adrienne Watson, a spokeswoman for the White House National Security Council. Representatives of the CIA and State Department also denied the report.
The pipelines are multibillion-dollar infrastructure projects designed to carry Russian gas to Germany under the Baltic Sea.
Sweden and Denmark, in whose exclusive economic zones the blasts occurred, both concluded the pipelines were blown up deliberately, but have not said who might be responsible.
The US and Nato have called the incident an act of sabotage. Moscow has blamed the West for the unexplained explosions that caused the ruptures. Neither side has provided evidence.
On Wednesday, Russia's Foreign Ministry said the US had questions to answer over its role in explosions at the pipelines.
Construction of Nord Stream 2, designed to double the volume of gas that Russia could send directly to Germany, was completed in September 2021.
But it was never put into operation after Berlin shelved certification just days before Moscow sent its troops into Ukraine last February.
Hersh is a former New York Times and New Yorker reporter who won awards for his investigative journalism, including about the Vietnam War and the 2004 Abu Ghraib prison scandal after the US invasion of Iraq.
More recently, he sparked controversy with a report disputing the Obama administration's version of the 2011 killing of Al Qaeda founder Osama bin Laden in a US special forces operation.
Hersh also caused concern with a report accusing Syrian rebels of staging an August 2013 sarin nerve agent attack on a Damascus suburb, which killed hundreds of civilians.
