LUCKNOW, India (Reuters) - The death toll in a train accident in northern India climbed to 80 on Monday with more than 350 injured in one of the worst rail disasters to hit the country's troubled rail network in years.

The accident occurred on Sunday in northern Uttar Pradesh state after the New Delhi-bound Kalka Mail suddenly stopped, derailing over a dozen carriages that smashed and piled into one another. Rescue teams and army officers struggled for over 24 hours to locate and remove bodies from the wreckage.

"It was one of the most serious cases of rail accidents in India," said Sandeep Mathur, chief public relation officer of North Central Railways, who added an inquiry would be launched.

Two Swedish nationals were among those killed, said Mathur.

The rail disaster comes with the beleaguered administration of Prime Minister Manmohan Singh poised to make minor changes to his cabinet this week, counting on veteran finance and interior ministers to help battle policy paralysis and public graft.

Adding to the political heat faced by Singh -- already reeling from a massive telecoms license corruption scandal -- was criticism that coalition ally Mamata Banerjee, who recently quit as railways minister, had neglected her core rail portfolio to concentrate on a local election campaign in West Bengal.

"The railway ministry has been functioning without any cabinet minister for about two months since Mamata Banerjee took over as West Bengal's Chief Minister. This shows the lackadaisical attitude of the (ruling coalition) government toward people's safety," said Vijay Pathak, a leader of the main opposition Bharatiya Janata Party (BJP) in Uttar Pradesh.

India's state-run rail monopoly is a vital national transportation grid for the country's 1.2 billion people, cramming 18 million people a day on to aging trains.

But decades of low investment, a patchy safety record and frequent delays mean India has fallen far behind China in building a network fit for Asia's third-largest economy.

In a separate accident, around 50 passengers were injured, many critically, after a suspected bomb blast derailed a train late on Sunday in the north-eastern state of Assam.

Some 336 people were killed and 437 injured in rail accidents in India between April 2010 and mid-January 2011, according to the latest government figures.

(Writing by James Pomfret; Editing by Paul de Bendern)

Source: Reuters US Online Report World News