The allegations, if lodged, could be included in the investigation into Mr Raab being carried out in to two formal complaints of bullying by senior lawyer Adam Tolley KC.
A source confirmed multiple senior officials who worked closely with Mr Raab, who denies bullying, were preparing to submit the complaints.
Liberal Democrat chief whip Wendy Chamberlain demanded an investigation after it also emerged Mr Raab had used his personal email account for Government business.
Allies of the Justice Secretary insisted there were no breaches of the ministerial code because he copied in an appropriate Government email address when required by the guidance.
They also argued he was using his personal account just to approve tweets and quotes with his team at short notice, and for political material.
But Ms Chamberlain said: “The public deserve answers, not more cover-ups.
“The Deputy Prime Minister cannot be relaxed about national security especially at a time when Britain’s enemies are stepping up their cyber attacks.
“It is only right and proper the Cabinet Office investigate these reports and determine immediately if overseas enemies could have seen national secrets sent by Dominic Raab.”
But Downing Street backed Mr Raab and rejected suggestions the investigation would be a whitewash, despite Mr Sunak’s ability to reject its findings.
“It’s a long-standing convention that the prime minister of the day is the arbiter of the (ministerial) code and the final decision-maker on these sorts of issues,” the Prime Minister’s official spokesman said.
“The investigator looking into this is highly experienced and has a suitable background and is being given access to whatever they need to conduct a thorough and swift investigation.”
The spokesman also defended Mr Raab over his email use, after Newsnight shared allegations he used his personal email account for Government business at two different departments, as recently as last year.
“Ministers are able to use various forms of communication,” he said.
“As long as they take heed of that guidance, there is not a binary restriction on use of personal email addresses.”
Deputy Labour leader Angela Rayner said: “There must be no hint of a whitewash when it comes to the slew of serious allegations the Deputy Prime Minister now faces.
“The scope of this investigation must immediately be expanded to enable proactive investigation of Dominic Raab’s behaviour during his time as a minister, including so-called expressions of concern, informal complaints and the concerning testimony of his own former permanent secretary.”