A train ran off the tracks in India's eastern state of West Bengal, killing at least two people and injuring six, a railways spokesman said on Wednesday, reviving concerns about safety just weeks after a crash that killed about 150 people.

India's state-run rail system, the world's fourth-largest and a lifeline for millions of poorer travelers, has struggled under growing demand and a lack of investment in upgrades.

The train, traveling from the eastern city of Patna to the northeastern city of Guwahati, left the tracks in the district of Alipurduar late on Tuesday, the spokesman said.

"A full investigation will take place," Anil Saxena told Reuters.

India's deadliest rail crash in years on Nov. 20 prompted a request from the railways to the finance ministry for about $17.5 billion to set up a dedicated safety fund, in addition to record investment pledged by Prime Minister Narendra Modi's government to modernize the network.