KOLKATA, January 19, 2012 (AFP) - An Indian high school teacher, with a monthly salary of around $700, was astounded when a routine online check of his bank account showed a balance of almost $10 billion.

Parijat Saha, from the town of Balurghat in West Bengal state, said he had checked his State Bank of India account online last Sunday to confirm reception of a 10,000 rupee ($200) interest payment.

"Instead I saw this astronomical amount," he told AFP by telephone.

The account showed a balance of 496 billion rupees.

After recovering from the initial shock at becoming an overnight billionaire -- at least on paper -- Saha, 42, said he immediately called a friend he knew at the bank to point out what was obviously a major accounting error.

The State Bank of India said it was not immediately clear how the amount came to be registered in Saha's account.

"We are trying to ascertain what went wrong," said local branch manager Subhashish Karmakar.

"We have informed our regional headquarters in Kolkata and national headquarters in Mumbai," he said.