The use of a spare business jet by former General Electric CEO Jeff Immelt was kept from board members until just this month, The Wall Street Journal reported on Sunday — a practice that reportedly drew internal scrutiny several years ago and that Immelt himself claims he didn't know about.

The Journal reported that the company had curbed the backup jet's use in mid-2014, adding that its use was in fact limited to isolated locations that involved potentially risky travel. However, he board members were previously unaware, several sources told the WSJ.

The situation came to light earlier this month, after The Journal reported that Immelt, who was at the helm of GE for nearly 20 years before being stepping down recently, sometimes utilized a backup plane to follow his regular corporate jet on several trips around the world.

However, sources familiar with the matter told CNBC a couple of weeks ago that version was an exaggeration of Immelt's travel practices.

These people told CNBC it was not a regular practice to fly, or even keep on standby, multiple planes at the same time. The sources said a second plane was kept on standby on the ground in certain locations while Immelt was visiting for security purposes, or in case his GE-owned plane had mechanical issues.

Last week, Immelt told the Journal that he was unaware of the backup jet's use. "This is not a practice I would have allowed," he said in an emailed statement to the publication.

In response to CNBC's request, there was no additional comment from either GE or Immelt beyond what was said in the Journal article.

A GE spokeswoman told the Journal, "This practice, which GE has discontinued, involved business-critical itineraries with tight schedules, multiple international stops and, in most cases, security concerns."

"We do not believe that the understandable criticism of this discontinued practice fairly reflects on Jeff's dedicated service to GE for over 30 years," she said, referring to Immelt.

—CNBC's Morgan Brennan and Michael Sheetz contributed to this article.

The Journal's full story can be found on its website.