Two babies have died in the last week and another is under intensive care in hospital after receiving hepatitis B vaccinations in central China's Hunan Province, the provincial health department said on Friday.

Zhang Shujun, senior doctor with the immunization program of the Hunan Disease Control Center, said the infants, from three different counties in Hunan, took vaccines produced by the same company -- Biokangtai.

Zhang said the vaccine produced by the Shenzhen-based producer has been used in Hunan for several years. The provincial health bureau and disease control center has started to investigate the babies' deaths.

Vaccination has been a key part of a successful national strategy to combat viral hepatitis in China, with the practice encouraged by the World Health Organization.

The vaccination for newborns is taken in three stages. The first shot must be taken immediately after birth. The second and third shots of the vaccine are taken after a baby is one month and then six months old, respectively.

Zhang said hepatitis B vaccines can have side effects that may be linked to the deaths.