OSAKA -- Snow Brand Milk Products Co., whose low-fat milk was blamed for widespread food-poisoning in western Japan last week, may have tried to cover up the possible contamination of other products, police sources said Wednesday.

On Tuesday, Snow Brand said it would recall all products manufactured at its Osaka plant after the city's public health center ordered that two low-fat, calcium-enriched milk products be collected by the company. A recall order had already been issued for one low-fat product.

The center issued the order Tuesday after finding that the two products -- Mainichi Honebuto and Yukijirushi Cal Power -- could also be contaminated.