Claims that Clive Lewis registered website addresses in apparent preparation for a Labour leadership bid have been denied by a source close to the MP.
It comes after the Huffington Post UK said four domain names which appeared to support Mr Lewis for Labour leader were registered on June 29, two days after he was appointed to Jeremy Corbyn's top team as shadow defence secretary.
The website addresses were: cliveforleader.co.uk, cliveforleader.org.uk, cliveforlabour.co.uk and cliveforlabour.org.uk, and according to the Huffington Post were registered to "Clive Lewis".
The Norwich South MP initially told the Huffington Post: "A lesson from LBJ (ex-US president Lyndon B Johnson) in how to smash an opponent.
"Legend has it that LBJ, in one of his early congressional campaigns, told one of his aides to spread the story that Johnson's opponent f***** pigs. The aide responded: 'Christ, Lyndon, we can't call the guy a pigf*****. It isn't true.'
"To which LBJ supposedly replied: 'Of course it ain't true, but I want to make the son-of-a-bitch deny it.'"
Later, a source close to Mr Lewis told the Press Association "categorically it is not true" that the MP registered the websites in preparation for a leadership bid.
"It is just even more silliness, there is clearly a concerted effort to undermine him," the source said.
The then-shadow business secretary was the most high-profile rebel to resign from Mr Corbyn's top team ahead of defying the leader's orders so he could vote against triggering the formal Brexit process.
Mr Lewis's actions provoked claims he was sounding out colleagues about a possible leadership run, but he rejected such talk.
"There has been speculation about that, and it is just that. You can quote me on this. It is total bollocks," he told the Eastern Daily Press earlier this month.
Mr Lewis was a staunch backer of Mr Corbyn as Labour leader after being elected in 2015.