Michael Flynn sent a text to a business partner as President Donald Trump was delivering his inaugural address last January that a joint plan between Russian Federation and Flynn's business allies to build nuclear power plants in the Middle East was "good to go".
The allegation - which suggests the Trump administration was eager to lift sanctions imposed by President Barack Obama and that Flynn may have blurred his public and private roles during his brief run at the White House - was outlined in a letter Cummings sent to Rep.
The Maryland Democrat said he considered "credible" the allegations that Flynn "sought to manipulate the course of worldwide nuclear policy for the financial gain of his former business partners".
The whistleblower also said that within minutes of Trump's inauguration ceremony, Flynn communicated directly with business associates about plans to begin building nuclear reactors in the Middle East-a joint project with Russian Federation, according to the letter. He called for a bipartisan investigation.
Flynn's attorney did not immediately respond to a request for comment.
According to Cummings, on January 20, 2017, the whistleblower had a conversation with Alex Copson, managing director of nuclear power promoter ACU Strategic Partners, as they attended Trump's inauguration.
The message said the project was 'good to go.' It continued that Copson should contact colleagues to 'let them know to put things in place.' The whistleblower could not read the text of the message, but said the timestamp said 12:11 pm, meaning just minutes after Donald Trump assumed the presidency.
Cummings also said the whistleblower quoted a business associate of Flynn as saying the economic sanctions against Russian Federation imposed by former President Barack Obama would be "ripped up" as Flynn's first order of business as Trump's national security adviser.More news: IATA says Middle East airline net profit will double in 2018
Flynn, a retired Army lieutenant general and former high-ranking intelligence officer, pleaded guilty last week to lying to the Federal Bureau of Investigation about his discussions with the then-Russian ambassador, Sergey Kislyak, about the sanctions that day after they were imposed.
"Mike has been putting everything in place for us", Copson said, according to the whistleblower.
Copson showed the witness the text on his phone. He was ousted as national security advisor after only 24 days on the job.
Media captionAfter Flynn's guilty plea, what next for the Russian Federation investigation?
The letter says Flynn blamed Obama for having 'f***** everything up in my nuclear deal with the sanctions'.
The office of special counsel Robert S. Mueller III was aware of the witness's account and asked Cummings not to release the information until the special counsel had taken "certain investigative steps", which are now complete, Cummings wrote. The whistleblower isn't named, but Cummings promised in the letter to share the person's identity with Gowdy if it remains confidential and Gowdy agrees to speak with the whistleblower.
Mr Flynn was a consultant to the firm for 14 months from 2015-16, according to amended financial disclosure forms he filed in August this year.