NEW DELHI -- A mystery epidemic has killed 44 Indian children in just over a month, medical officials said on Saturday.

A team from the country's National Institute of Communicable Diseases has rushed to the Saharanpur area of the country's most populous state, Uttar Pradesh, to investigate the outbreak, local chief medical officer Dr.

Ghanshayam Singh said.

"It is difficult to ascertain the exact cause of the spreading epidemic and a team from the National Institute of Communicable Diseases has taken the blood samples to look in to the matter," he told Reuters by phone from Saharanpur, 185km (115 miles) from New Delhi.

Saharanpur residents have blamed the epidemic on poor sanitation but local officials have accused parents of taking their sick children to unqualified people for treatment.

"The condition in the villages is very bad and I think at least 100 to 115 children may have died," Vinay Yadav, the father of a sick child, told Reuters television.

Some doctors say the symptoms of headache and fever point to the mosquito-borne Japanese encephalitis, although there was no official confirmation.

"Most cases are of children in the age (group) of one to five years and the common complaint is that of headache and fever," Singh said.