Donald Trump on Tuesday fired the government’s top election security official, who had rejected the president’s unsubstantiated claims of “massive” fraud in the vote he lost to Joe Biden.

Trump announced on Twitter the termination “effective immediately” of Chris Krebs, who leads the agency that jointly declared “the Nov 3 election was the most secure in American history”.

Trump, who refuses to acknowledge that he lost his bid for reelection to Democrat Biden, has repeatedly claimed without evidence that the voting and count were replete with fraud.

“The recent statement by Chris Krebs on the security of the 2020 Election was highly inaccurate, in that there were massive improprieties and fraud,” Trump wrote in a tweet.

“Therefore, effective immediately, Chris Krebs has been terminated as Director of the Cybersecurity and Infrastructure Security Agency.”

Krebs, who reportedly told friends last week he expected to be removed, appeared to confirm it in a tweet on his personal account.

No evidence

“Honored to serve. We did it right. Defend Today, Secure Tomorrow,” he wrote.

Krebs was in charge of fending off possible foreign and domestic hacker intrusions into myriad voting machines, sorting and counting machines, databases and other systems that states and localities rely on to tally ballots.

Adam Schiff, the Democratic chairman of the House Intelligence Committee, said Krebs and his team had “worked diligently to safeguard our elections”.

“Instead of rewarding this great service, President Trump is retaliating against Director Krebs and other officials who did their duty,” he said in a statement.

Republican Senator Ben Sasse wrote: “Chris Krebs did a really good job – as state election officials all across the nation will tell you – and he obviously should not be fired.”

The challenge was even tougher this year because of the complexities of the coronavirus, which forced a sweeping turn to voting by mail.

Under Krebs, CISA had also warned several times that Russians and Iranians were making attempts to break into US systems, as Russians had tried in 2016.

The White House was reportedly particularly unhappy about a CISA webpage set up to fight disinformation called “Rumor vs Reality”.

The page rejected claims Trump and others have made, including that many votes were made in the names of dead people, that counting the ballots days after election day is not normal and that shifting vote counts indicate fraud.

Through numerous reviews, investigations and lawsuits, no evidence has come up of any significant distortion or loss of votes, by accident or fraud.

“There is no evidence that any voting system deleted or lost votes, changed votes, or was in any way compromised,” an official group of senior US federal and state election officials said in a report last week.

And on Monday, a group of 59 top election security experts also dismissed claims of significant malfunction or fraud, saying the claims “either have been unsubstantiated or are technically incoherent.”