A salmonella outbreak linked to a popular Kellogg's cereal has infected 100 people, the Centers for Disease Control and Prevention (CDC) announced on Thursday.

The agency is urging consumers to avoid Honey Smacks, a sugary puffed wheat cereal which has been the subject of a recall by the company since mid-June. At least 30 of the 100 have been hospitalised, while no deaths have been reported, the CDC said.

"Do not eat Kellogg's Honey Smacks cereal of any size package or with any 'best if used by' date," it wrote.

"Do not eat this cereal," the CDC said bluntly in a tweet.

The agency has said that it has found salmonella stains in unopened and leftover samples of Honey Smacks. Though the recall covers cereal with a best-by date of June 14, 2018, through June 14, 2019, the agency is recommending people avoid the cereal altogether.

According to Reuters, the company recalled an estimated 1.3 million cases of the cereal but the FDA said on Thursday that it believes the cereal is still being sold by some stores.

This is not the first time Kellogg's has recalled Honey Smacks - a salmonella outbreak in 2010 which affected 73 people prompted the company to issue a recall notice (AP)

"Retailers cannot legally offer the cereal for sale and consumers should not purchase Kellogg's Honey Smacks cereal," it wrote.

The cases have been reported in 33 states, including New York, Pennsylvania, Texas, California, Maryland and Virginia.

According to the CDC, Salmonella is responsible for about 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths a year, the majority of which are sourced from food. Symptoms for salmonella infection, which lasts about four to seven days, include diarrhoea, fever and abdominal cramps.

Kellogg Company, which did not respond to an immediate request for comment, launched an investigation into a third-party manufacturer who produces the cereal in mid-June after the infections were reported, according to the FDA. The FDA inspected the site and said that samples taken on the site matched the outbreak strain.

The recall effort follows other prominent salmonella outbreaks, including one linked to pre-cut melon from an facility in Indianapolis that sickened 70 people and another connected to eggs from a single North Carolina producer where 45 people were made sick. Earlier this year, 210 people were infected by an E. coli outbreak that killed five people linked to romaine lettuce that had been grown in Arizona.