Top hedge fund manager Dan Loeb is unimpressed with Nestle's efforts to up its game.

The billionaire investor is accusing the Swiss-based global food giant — whose brands include KitKat chocolate bars and Haagen-Dazs ice cream — of a "muddled strategic approach" and a lack of urgency in keeping up with competitors.

"Nestle's insular, complacent, and bureaucratic organization is overly complex, lethargic, and misses too many trends," Loeb wrote in a letter to the company's top management that was made public late Sunday.

His activist fund, Third Point, took a $3.5 billion stake in Nestle (NSRGF) a year ago, saying it would push for a new strategy to help the company improve its sales and profitability.

Nestle, which has a market value of around $235 billion, has since made some moves to address investors' concerns. It set new a profit target in September and agreed to offload more than 20 of its US candy brands in January.

But sales at its existing businesses grew just 2.4% in 2017, the slowest pace in more than two decades. Its share price has declined more than 8% so far this year.

Related: Nestle is paying $7.2 billion to sell Starbucks coffee

Loeb said the changes Nestle is making are too small and too slow, expressing doubt that it can consistently meet its sales growth target with its current product lineup.

"We are concerned that Nestle does not fully appreciate the rapidly occurring shifts in consumer behavior that threaten its future," he wrote. Third Point has set up a dedicated website, NestleNOW, to press its case, including a 34-page presentation.

In a statement Monday, Nestle insisted its board and management are "delivering results" through "swift and decisive action." It listed a series of steps it has taken since last year, including investing in key brands and a global coffee partnership with Starbucks (SBUX).

The company said it welcomes "continued input" from shareholders.

In February, Nestle CEO Mark Schneider said he saw "a broad consensus among investors that we're going in the right direction and that we're going at a pace that is commensurate with the size of the company."

Related: Nestle sales growth slowest in decades

Loeb disagrees. In his letter, he called on the company to split itself into three key divisions, based around beverages, nutrition and groceries. The fund's presentation urged Nestle to sell or spin off "weak and non-strategic" businesses, highlighting brands like Dreyers ice cream and Hot Pockets as examples.

Loeb said Nestle should offload as much as 15% of its businesses and also reiterated his call for the company to sell its 23% stake in cosmetics firm L'Oreal (LRLCF).

The proceeds should be used to buy smaller brands in fast growing areas or for share buybacks, he wrote.

Third Point has previously taken big stakes in companies such as Yahoo, Sony (SNE) and Sotheby's (BID).

It has gotten credit for boosting the stock market value of its investments based on its activist approach, but things haven't always gone its way.

For example, the fund's investment in Sony in 2013 and 2014 barely moved the needle on its share price.

-- Alanna Petroff contributed to this report.