A bipartisan group of senators is calling on Congress to further investigate reports that Russia worked to influence the presidential election in favour of President-elect Donald Trump. Senators Charles Schumer, Jack Reed, John McCain and Lindsey Graham said in a joint statement that the CIA's report about Moscow's alleged interference should "alarm every American".

"Congress's national security committees have worked diligently to address the complex challenge of cybersecurity, but recent events show that more must be done," the four senators said.

"While protecting classified material, we have an obligation to inform the public about recent cyberattacks that have cut to the heart of our free society. Democrats and Republicans must work together, and across the jurisdictional lines of the Congress, to examine these recent incidents thoroughly and devise comprehensive solutions to deter and defend against further cyberattacks."

The statement comes on the heels of Trump's adamant denials that the report could be true. Earlier in the day, the president-elect appeared on Fox News Sunday to say he does not believe the report by the intelligence agency that Moscow helped influence the election in his favour. "I think it's ridiculous. I think it's just another excuse. I don't believe it," he said.

"I think the Democrats are putting it out because they suffered one of the greatest defeats in the history of politics in this country," Trump added. NPR noted that while Trump's victory was definitely an upset, it was not historic in size.

In an interview on CBS's Face the Nation, McCain, an Arizona Republican, urged Trump to accept the CIA's report. "The facts are there," McCain said. "Now whether they intended to interfere to the degree that they were trying to elect a certain candidate, I think that's the subject of the investigation," he continued. "But facts are stubborn things - they did hack into this campaign."

McCain argued that the issue is bigger than partisan politics as it affects free and fair elections, NPR reported. The senator's Armed Services Committee will begin working on the investigation right away, though McCain said he would prefer a special committee to lead the investigation.

"We'll go to work on it, we'll go to work immediately because the issue of cyber is not a static issue," he said. "You can't make this issue partisan, it's just - it's too important. A fundamental of a democracy is a free and fair election."

According to NPR, Republican Congressman Michael McCaul of Texas has also called for an investigation. Congressmen Peter King of New York and Devin Nunes of California said they also believe Russia is behind the cyberattacks.

President Barack Obama ordered on 9 December a full review of "malicious cyber activity" during the election, to be completed before Trump assumes office on 20 January. The president's order came hours before The Washington Post released its story about the CIA's findings.