At least 19 people have been killed and dozens injured when a bus full of passengers was struck by a train in Pakistan's southern Sindh Province.

Railway official Tariq Kolachi said on February 28 the accident took place near the district of Rohri, some 470 kilometers north of Karachi, at an unmanned crossing.

"All those killed and injured were passengers from the coach," he said.

At least 55 people were injured, Rana Adeel, a deputy commissioner in Sukkur, told AFP. He warned that some of the injured were in critical condition and that the death toll could rise.

Kolchi said the cause of the crash remained unclear, adding that the passenger train, called the Pakistan Express, was traveling to Lahore from Karachi.

"Apparently the accident took place due to the bus driver's negligence," Railways Minister Sheikh Rashid Ahmad said, but added that an inquiry was under way to clarify what had happened.

Railway safety in Pakistan has deteriorated over recent decades, hurt by corruption, mismanagement, and lack of investment.

Based on reporting by AP, AFP and dpa