At least 90 people have been killed after 14 carriages of an Indian express train derailed in northern Uttar Pradesh state, police say.

The incident took place on the Indore-Patna Express just after 03:00 local time on Sunday (21:30 GMT Saturday) near the city of Kanpur.

Rescuers cut their way through the twisted carriages to retrieve bodies and rescue the injured.

More than 120 people have been reported injured.

It was not immediately clear what caused the coaches to derail.

Krishna Keshav, who was travelling on the train, told the BBC: "We woke with a jolt at around 3am. Several coaches were derailed, everybody was in shock. I saw several bodies and injured people."

Most of the victims were located in two carriages near the engine which overturned and were badly damaged, reports said.

Rescue workers at the site were using heavy machinery to cut through the carriages to reach survivors.

"Many more passengers are trapped," said Anil Saxena, a senior railway official in New Delhi.

Indian prime minister Narendra Modi tweeted: "Anguished beyond words on the loss of lives due to the derailing of the Patna-Indore express. My thoughts are with the bereaved families.

"Prayers with those injured in the tragic train accident."

Modi said he had spoken to Railways Minister Suresh Prabhu, who was "personally monitoring the situation closely".

(BBC)