Taiwanese rescue teams continued efforts Monday to retrieve the last remaining body of the train passengers killed in a deadly crash last week, as the nation continued mourning the worst train accident in decades.

The crash had occurred after a packed express train carrying almost 500 passengers and crew slammed into a truck near the eastern city of Hualien Friday, causing it to derail and the front end to crumple, killing 50 people. It was the island's worst rail accident in seven decades.

The truck had slid down a sloping road from a building site onto the tracks just outside a tunnel. Officials suspect the truck's brakes were not properly applied, and are investigating the manager of the site.

Hualien's fire department said that the remaining body was trapped under a 15-tonne train bogie. It did not provide details on the identity of the passenger. "The rescue is difficult, and we are currently discussing how to overcome these difficulties, so the time it takes may be delayed," the department said.

The government said the fifth carriage had been removed, with the other three expected to be extracted by Tuesday, reported Reuters.

Transport Minister Lin Chia-lung said late Sunday that he took responsibility for the accident and would step down once initial rescue and recovery work was complete.

Premier Su Tseng-chang on Monday welcomed Lin's "responsible" attitude. "However, rescue and re-opening work are the most important things at this stage. As for the issue of follow-up responsibilities, it has not yet been discussed," he told reporters in Taipei.

The victims include two Americans and one French national.

Taiwan's government has promised compensation and said it would do everything it could to help survivors and their relatives, including coordinating public donations. The presidential office said President Tsai Ing-wen, Vice President William Lai and Su had all donated a month's salary.

The damaged section of the track is not expected to reopen until April 20 at the earliest, though rail traffic continues on a parallel track that runs through another tunnel that was not affected by the accident.

The crash occurred at the start of a long weekend for the traditional Tomb Sweeping Day, when people return home to tend to family graves.

Taiwan's worst train crash was in 1948 when 64 people are estimated to have died in a fire.