New Delhi - At least 13 passengers were charred to death and six injured Friday when a fire broke out in a moving train in India's southern state of Andhra Pradesh, officials said.

The fire broke out in one of the coaches of the Gautami Express and spread to four other compartments as the train moved through the northern district of Warangal.

"The fire completely gutted the coaches," said AK Saxena, chief spokesman of the Indian Railways.

"The death toll could rise as three of the wounded are in a serious condition," he said.

The victims included a pregnant woman and three physically disabled people. The injured were rushed to government hospitals for treatment.

Railway officials said the rescue teams had reached the scene 250 kilometres north-east of the state capital, Hyderabad and detached the burning coaches from the train.

Local media reported that the fire erupted because of a short circuit, but there was no official confirmation of the cause.

"We cannot determine the cause of the fire right now," Saxena said. "The commissioner of railway safety has been tasked to investigate the accident."

The spokesman added that forensic teams had already reached the accident site.

Indian Railways runs one of the largest rail networks in the world and reports an average of 250 accidents each year.

Every day more than 8,500 trains carry 13 million passengers over 3,000 kilometres of railway across India.

The state-run railway is in the process of upgrading its infrastructure, bridges and signals. (dpa)