British Transport police (BTP) have apologised for accidentally forwarding a message that was meant for the survivors of a tram crash in south London to dead victims.

The invitation, asking if other survivors would like to meet to discuss their experiences, had been written by the widow of one of those killed in the crash in Croydon on 9 November 2016. Some 51 people were injured, some seriously, in the derailment, which is still under investigation.

BTP is investigating how the addresses of those killed - Donald Collett, Philip Logan, Robert Huxley, Phil Seary, Mark Smith, Dorota Rynkiewicz, and Dane Chinnery - were included in the mail out.

BTP said in a statement to the Evening Standard: "We are working hard to ensure that everyone involved in the Croydon tram derailment is receiving the support they need and sent out letters to invite people to a forum being organised by one of the survivors.

"Due to human error, this list of people we provided included the bereaved families. As soon as this was realised, we immediately contacted each family through their specially trained officers to ensure they had warning before it arrived. We are sorry for absolutely any unnecessary hurt this may have caused them."

This is the latest in a series of gaffes made by BTP since the crash. The family of Philip Logan were visited by a liaison officer who apologised for leaking his name to the media before informing the family.

According to The Telegraph, the bereaved families also claim they did not receive the second interim report by the Rail Accident Investigation Branch into the crash before it was made public. The Branch maintains copies were posted to all the families.

Croydon tram accident
Members of London Fire Brigade look at the overturned tram near Sandilands Tram stop in Croydon Carl Court/ Getty Images