The Beijing Municipal Industrial and Commercial Bureau said it had received complaints from dozens of pet owners whose cats had also died or become seriously ill after eating the suspect brand of cat food.
Another animal volunteer, Ding Shiying, who has fed homeless cats for more than 60 years, said she had received many complaints over the cat food.
"I'm sure the cats died of food containing heavy metals, food which was made with polluted seafood ingredients," Ding said, according to the paper.
The paper quoted an agricultural ministry official as saying there were no regulations for pet food ingredients in China.
China's waterways have suffered from more than two decades of economic growth that has paid little heed to the environment.
A report last week said dangerous levels of heavy metals had been found in 41 percent of seafood in one of the eastern province of Jiangsu, one of China's major fish-producing areas.