The sources of 39 types of inferior milk powder, including 48 brands, have been found, local police in east China's Anhui province said Wednesday.

Chen Xiaoping, deputy director of the provincial public security department, said that as of April 28, the Anhui police have destroyed three workshops producing substandard milk powder and investigated three major dealers of the milk powder.

The police have filed 34 cases and captured 39 suspects, Chen said.

The local police have dispatched 16 teams to Heilongjiang, Zhejiang, Shandong, Shaanxi, Jiangsu, Fujian and Henan provinces and Beijing municipality to investigate and destroy the sources, according to Chen.

Thirteen infants in Anhui have died of nutritional deficiencies from consuming substandard milk powder, and 171 infants suffered from malnutrition after being fed with milk powder deficient in protein and other nutrients. Two are still being treated in hospital.

The majority of them live in rural areas in Fuyang city. The parents bought cheap milk powder which contained little nutritional ingredients at rural shops in Fuyang. The babies heads swelled and their bodies failed to grow properly.

The news had extensive repercussions after it was broadcast on television April 19. The Anhui Provincial government issued an urgent circular on April 20, calling for immediate rectification of the milk powder market and severe punishment of law breakers.

At a meeting held on April 20 by the State Council, the central government, Chinese Premier Wen Jiabao ordered that a special teams should be dispatched immediately to Fuyang to investigate the accident.

The inspection showed 45 types of substandard milk powder were sold on the retail market in Fuyang city. They were produced by 141 factories in Heilongjiang, Zhejiang, Shandong, Hebei, Hubei and Jiangxi provinces, Beijing and Shanghai municipalities and Inner Mongolia Autonomous Region. The products are sold in 149 brands.

So far, Fuyang city has confiscated 6,110 bags of inferior milk powder and sealed 12,862 bags of milk powder. Investigation of key milk powder wholesale agents is underway. Police in Fuyang have also detained five principal wholesale dealers who sold substandard milk powder that led to the death of 13 infants.