Israeli Prime Minister Benjamin Netanyahu has flatly denied a report that his country was spying on the US.
A Politico article cites three former senior US officials who say Israel was likely to be behind surveillance devices found near the White House.
But a statement from Mr Netanyahu's office said this was "a blatant lie".
"There is a longstanding commitment, and a directive from the Israeli government not to engage in any intelligence operations in the US."
President Donald Trump, asked by reporters about the report, said he did not believe Israel was spying on the US.
"I really would find that hard to believe, my relationship with Israel has been great," Mr Trump said, citing the end of the Iran nuclear deal and his administration's controversial decision to move the US embassy to Jerusalem.
"I wouldn't believe that story. Anything's possible but I don't believe it."
The allegations appeared in an exclusive story for US news site Politico on Thursday.
International mobile subscriber identity-catchers (IMSI catchers) - informally known as StingRays - were reportedly found near the presidential residence and by other sensitive sites across Washington DC during the Trump presidency.
These devices act like mobile phone towers, tricking phones into sending their location, identity information, and even call contents and data usage.
One of the former officials who spoke anonymously to the site said the StingRays were likely designed to spy on President Trump. He said it is not clear if they succeeded.
FBI counterintelligence agents conducted analysis to find out where they came from. "It was pretty clear that the Israelis were responsible," a former senior intelligence official told Politico.
This same official also criticised the Trump administration, saying they did not publicly or privately reprimand the Israeli government for the alleged spying.
"I'm not aware of any accountability at all," the former official said.
Despite Mr Netanyahu's denials, Israel has spied on the US in the past.
Rafi Eitan - a Mossad agent who captured Nazi Adolf Eichmann in 1960 - was exposed in the 1980s as the handler of Jonathan Pollard, a US analyst who gave thousands of top secret documents to Israel.
In 2006, former US Department of Defense employee Lawrence Franklin received a 13-year prison sentence for passing classified documents on US policy towards Iran to Israel. His sentence was later reduced to ten months' house arrest.