Citigroup is in the midst of a search for a new chief executive and is preparing to take additional write-downs. But the bank, which has struggled in recent years to contain expenses, has reportedly decided it can't wait to cut costs.

Charles Gasparino on CNBC reports that Citigroup is planning a second round of layoffs that could affect as many as 45,000 jobs.

In April, Citigroup, which employs about 327,000 worldwide, announced that it would cut 17,000 jobs and move another 9,000.  

A Citigroup spokesman, Mike Hanretta, told Reuters, "Our business heads are planning ways in which we can be more efficient and cost-effective to position our businesses in line with economic realities."

"Any reports on specific numbers are not factual," he added.