At least seven people were killed and more than 80 injured when two passenger trains collided in southern India on Tuesday, police and railway officials said. The accident occurred around 75 kilometers (45 miles) from the port city of Chennai around 9:30pm (1600 GMT) when one train slammed into the back of another that was standing stationary at a signal point.Three carriages were derailed in the impact. \"We have confirmation of seven dead so far,\" said police Inspector General Syleendra Babu. More than 80 people were reported injured, some of them seriously. Some TV reports had put the death toll as high as 15. Briefing reporters in New Delhi, Indian Railways Minister Dinesh Trivedi said the final casualty figure had yet to be confirmed, but added that the rescue operation had been completed with emergency teams cutting their way into all the damaged carriages. \"The precise cause of the accident cannot be ascertained at the moment,\" Trivedi said, adding that he would be travelling to the accident site on the first available flight. India\'s state-run railway system -- still the main form of long-distance travel despite fierce competition from private airlines -- carries 18.5 million people every day. While new shiny airport infrastructure is springing up across the country, the Indian railways -- a much romanticised legacy of British colonial rule -- often appear stuck in a time-warp. After decades of under-investment, the rolling stock is old, speeds are low, signalling is done manually in some areas, and a lack of fencing makes the network a soft target for militants. The last major accident occurred in July when a packed express train travelling from Kolkata to New Delhi derailed at high speed in the northern state of Uttar Pradesh, killing 63 people. The worst accident was in 1981 when a train plunged into a river in the eastern state of Bihar, killing an estimated 800 people. The last railways minister, the arch-populist Mamata Banerjee, announced in February a 40 percent hike in the annual railway budget to 576 billion rupees ($12.9 billion). But critics say successive budget hikes have failed to improve safety records, as only a miniscule amount is spent on upgrading key areas such as signalling and track maintenance. Indian Railways has an engorged payroll and is financially inefficient with operating costs, including salaries, accounting for more than 90 percent of revenue.