Abbott Laboratories posted a list of lot numbers on Thursday for the millions of recalled containers of its Similac powdered infant formulas and expanded Internet and call center capacity to handle a deluge of requests for information from concerned parents.

The company announced a voluntary recall on Wednesday of about 5 million units of its top-selling powdered infant formula after beetles were found in the products and in a Michigan plant where they are made.

The Abbott website was so busy after the recall that it crashed Wednesday night, hampering efforts by parents to find out if they had been feeding their babies tainted formula.

Abbott said it was aware of the amount of calls and website traffic, and that it had increased its call center resources and the bandwidth of its websites.

While Abbott did not expand the recall, it did have more details, including that all Similac powder formula sold in rectangular tubs had been recalled.

Consumers who purchased the powder formula in cans or other packaging were directed to the list of recalled lot numbers. The lot numbers involved in the recall can be found at abbott.com, abbottnutrition.com, similac.com, and similac.com/recall, the company said.

If consumers have formula being recalled, they should discontinue use of the product immediately and visit a local store to purchase a Similac liquid product or an alternative infant formula to feed their child, Abbott said in a statement.

The company said it would reimburse consumers who return potentially tainted formula.

The recall is limited to the United States, Puerto Rico, Guam and some countries in the Caribbean, Abbott said.

Shares of Abbott closed down 39 cents at $51.60 on the New York Stock Exchange.

Michigan