Swiss medical authorities said on Monday that the condition of two Japanese holidaymakers who were critically injured when a popular tourist train derailed in the Alps was improving.

A 64-year-old Japanese woman was killed and about 42 people were injured when first-class carriages of the scenic Glacier Express travelling between the ski resorts of Zermatt and St Moritz overturned on Friday.

Thirteen people, including 12 Japanese and a Spanish national, were still hospitalised in western Switzerland on Monday, Valais canton hospitals network said.

Of those, seven Japanese were listed as in a serious condition, including two breathing with the help of tracheal tubes, it added in a statement.

Hospitals network director Dietmar Michlig said that the two most seriously injured were still in intensive care, but “their clinical situation is improving,” he added.

Most of those still receiving treatment are suffering from multiple fractures, including spinal, hip and head injuries.

Michlig said at least four patients were expected to be discharged by the end of the week.

Valais police and federal authorities are still investigating the cause of the accident.

Services on scenic railway across the southern Swiss Alps resumed on Sunday.