Train door 'ripped from hinges' in Bangor tunnel
An investigation is under way after a train door was reportedly ripped from its hinges as it went through a tunnel.
No-one was hurt in the incident involving Monday's 0533 Holyhead to Cardiff Central service in Bangor at around 06:00 BST.
Rail operator Arriva Trains Wales said a "thorough investigation" had been launched.
The Rail Accident Investigation Board (RAIB) has also been informed.
Arriva Trains Wales said the door was found to be missing at Penmaenmawr.
Passengers were moved to the back of the train and the affected section was locked out of use before the train carried on to Llandudno Junction where it was taken out of service for examination.
Raising the issue in the assembly chamber on Tuesday, Welsh Liberal Democrat Shadow Transport Minister Eluned Parrott called on the Welsh government to urgently review train carriages in Wales to ensure they were safe for use.
"If passengers or staff had been standing in the area at the time of the incident - a common occurrence on our overcrowded trains - the consequences could have been far worse," she said.
In reply, Finance Minister Jane Hutt said control of railway rolling stock was not devolved but said the AM had highlighted "a very serious incident" which needed to be brought to the attention of the UK Department for Transport.