Closely watched bond investor Bill Gross criticized ultra-low interest rates on Monday, saying they could harm global growth instead of boosting it in the way that many central banks intend.

"Low interest rates globally destroy financial business models that are critical to the functioning of modern day economies," Gross, who oversees the Janus Global Unconstrained Bond Fund, wrote in his monthly investment outlook.

"Negative/zero bound interest rates may exacerbate, instead of stimulate, low growth rates ... by raising savings and deferring consumption," he wrote.

He said pensions funds and insurance companies were particularly "threatened by low to negative interest rates."

Central banks around the world, particularly in developed markets, have slashed interest rates in recent years to boost sluggish growth.

The U.S. Federal Reserve took rates to near zero during the financial crisis, and yields on bonds have remained historically low for years. The 10-year Treasury note currently yields around 2.0174 percent.

However, the Fed has been considering raising its key interest rate for the first time since 2006, a decision that has been complicated by global headwinds and subdued price pressures in the United States.

Gross suggested that the Fed could move to raise rates as soon as the second quarter, starting with gradual increases.

He advised investors to "stay conservative in your investment portfolio. Own high-quality bonds and low P/E (price to earnings), high-quality stocks if you want to stay out of the doghouse."

Known as the "Bond King" for his decades-long run of returns, Gross shocked fixed-income markets last year when he quit bond giant Pacific Investment Management Co (Pimco) on Sept. 26 for distant rival Janus.

Gross helped launch Pimco more than four decades ago and built it into a $2 trillion investment powerhouse. But lackluster returns more recently, outflows, and grumbles about his leadership style and personality dented his reputation.

Monday's letter, written in Gross' rambling style, opened with a lengthy discussion about different breeds of dogs and included a photo of his own golden retriever.

"Arf, Arf," he wrote. "Sometimes, when life seems to be going to the dogs, it's not necessarily a bad thing."