President Donald Trump on Saturday accused his predecessor Barack Obama of "wire tapping" his office in New York just before the 2016 presidential elections and likened the alleged surveillance of his communications to the "Watergate" scandal.
Trump made the allegations in a series of tweets, but did not provide any evidence to substantiate his claims.
"Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!" Trump said.
"Is it legal for a sitting President to be "wire tapping" a race for president prior to an election? Turned down by court earlier. A NEW LOW!," he said, claiming that Obama had defied a court rejection to tap his office.
Trump also called Obama a "Bad (or sick) guy!" and compared the alleged tapping of his New York office to the "Watergate", the scandal in the early 1970s which brought down President Richard Nixon.
"How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!" he said.
"I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to Election!" Trump tweeted.
There was no immediate reaction from the office of the former US president.
He also tried to defend Jeff Sessions, the US attorney general facing questions over his meeting with the Russian ambassador to Washington during the 2016 presidential election campaign.
"The first meeting Jeff Sessions had with the Russian Amb was set up by the Obama Administration under education program for 100 Ambs......," he said.
"Just out: The same Russian Ambassador that met Jeff Sessions visited the Obama White House 22 times, and 4 times last year alone," Trump said in another tweet.
Trump's top administration officials have been facing charges of contacts with Russian officials during and after elections.
One of his close aides General (retd) Michael Flynn had to resign following such allegations.