United States President Donald Trump on Monday claimed he has never worked for Russian intelligences agencies.

He was reacting to a New York Times report published last week that said the Federal Bureau of Investigation had started an investigation into the president’s alleged links to Moscow after former agency Director James Comey was fired in May 2017.

“I never worked for Russia, and you know that answer better than anybody,” Trump told reporters on the White House’s South Lawn, according to CNN. “It’s a whole big fat hoax. It’s just a hoax.”

He claimed the people behind the investigation were “known scoundrels” and “dirty cops”. The FBI has experienced a turnaround after Comey and agency officials Lisa Page, Peter Strzok and Andrew McCabe quit, he added.

According to The New York Times, the FBI wanted to investigate whether Trump’s actions constituted a threat to US national interests. FBI agents also attempted to find out whether Trump was knowingly or unwittingly working under the influence of Moscow. The investigation also considered whether the decision to sack Comey constituted obstruction of justice.

American intelligence agencies believe that Moscow influenced the result of the 2016 presidential elections in which Trump, the nominee of the Republican Party, stunned most pollsters by defeating Democratic Party nominee Hillary Clinton. In March 2017, the FBI started an investigation into alleged Russian meddling in the election. Russia has denied the accusations.