Republican and Democratic legislators 'yet to uncover evidence Susan Rice committed a crime'

Sources say Ms Rice's requests were 'normal and appropriate'

Critics have issued mounting calls for Donald Trump to be impeached (AP)

Both Republican and Democratic legislators are yet to uncover evidence Obama administration officials did anything unusual or illegal, CNN reports.

President Donald Trump had alleged Barack Obama's National Security Adviser Susan Rice may have committed a crime by requesting the "unmasking" of individuals in the Trump transition team.

Mr Trump called it "one of the big stories of our time."

However, after reviewing intelligence reports related to Ms Rice's requests at the NSA headquarters in Fort Meade, Maryland, several members and staff of the House and Senate intelligence committees have found no wrongdoing, multiple sources told CNN.

One described Ms Rice's requests as "normal and appropriate" for officials who serve as National Security Adviser.

Another said there is "absolutely" no smoking gun in the reports.

They reportedly urged the White House to declassify them to make clear there was nothing alarming.

Ms Rice denied any wrongdoing, telling MSNBC: "The allegations that somehow Obama administration officials utilised intelligence for political purposes are absolutely false."

According to five US intelligence officials talking to Reuters, Ms Rice followed standard procedure in requesting the NSA to reveal to her the names of American citizens who had been in contact with Russians whose communications were monitored by US intelligence.

It is unlikely she would have known that any unidentified American had a connection to Mr Trump, the officials said.

As White House national security adviser, Ms Rice could not order the NSA to reveal the identities of any Americans. Instead, she could only request it to do so.

There is nothing unusual, much less suspicious, about any request by Ms Rice, another intelligence official said, especially since it could have revealed Russian intelligence contacts or agents operating in the United States.

That official and two other intelligence officials said the NSA often receives dozens of such requests in a month.