A Chinese court has sentenced a dairy farmer to death for poisoning her competitor's milk supply with an industrial chemical that left three young children dead and another 36 sick.

The court in the northwestern province of Gansu found that Ma Xiuling deliberately added nitrite, an industrial salt, to fresh milk produced by her rival in April following a series of business disputes.

The woman's husband was also sentenced to life in prison for his involvement. Both plan to appeal their verdicts.

China has been hit with numerous food safety scandals in recent years, many involving the addition of dangerous additives to foods to lower the cost of production.

In 2008, at least six children died and nearly 300,000 were sickened by milk made from powder laced with melamine, an industrial compound that was added to give misleadingly high results in protein tests.