US President-elect Donald Trump said he didn't believe reports that intelligence agencies concluded Russia intervened in the presidential election on his behalf, according to an interview broadcast on Fox News.

“I think it's ridiculous. I think it's just another excuse. I don't believe it,” Trump said in the interview, taped on Saturday. He blamed Democrats for putting out the media reports and said he did not believe they came from the Central Intelligence Agency.

A senior US intelligence official told Reuters intelligence agencies have concluded with “high confidence” that not only did their Russian counterparts direct the hacking of Democratic Party organisations and leaders, but they did so to undermine Democratic candidate Hillary Clinton.

The Republican president-elect questioned whether the CIA was behind the reports that indicated Moscow wanted him in the White House. “I think the Democrats are putting it out,” he said in the interview.

Two leading Republican voices on foreign policy in the US Senate, John McCain and Lindsey Graham, joined two Democratic senators on Sunday in expressing concern over the reports on Russian interference and saying that cannot become a partisan issue.

“For years, foreign adversaries have directed cyber attacks at America's physical, economic, and military infrastructure, while stealing our intellectual property. Now our democratic institutions have been targeted,” the senators, including Democrats Chuck Schumer and Jack Reed, said in a statement.“Recent reports of Russian interference in our election should alarm every American.”

US intelligence agencies have told Congress and the administration of President Barack Obama that Russia has grown increasingly aggressive in Syria and Ukraine and has stepped up activities in cyberspace including meddling, sometimes covertly, in European and US elections.

“This cannot become a partisan issue. The stakes are too high for our country,” the senators said in a statement.