Chinese authorities have reportedly seized 38 tonnes of milk powder laced with melamine - the toxic additive that sparked a nationwide uproar in 2008.
The state news agency Xinhua says samples of powder found in two provinces in north-west China had melamine levels up to 500 times over the permitted limit.
Two years ago, at least six children died and nearly 300,000 fell ill from drinking powdered milk laced with melamine, an industrial compound added to bulk out the product.
The powder was sold mainly by the now-bankrupt Sanlu Group, which was partly owned by New Zealand dairy giant Fonterra. Two people were executed last November for their part in the scandal.
The latest batch of contaminated powder was first found in Gansu province and traced back to the Dongyuan Dairy Factory in Minhe Country, in neighbouring Qinghai.
The owner and a production manager at the factory have been detained.