Train operator Southern scored the worst levels of public trust out of all rail companies over the past two years, according to a new report.

Analysis by Transport Focus showed the firm was given "notably low scores for trust" across the last four passenger surveys, ranging from 17% in spring and autumn 2017 to 22% in the most recent survey in autumn last year.

These were the lowest scores out of all operators.

Southern has been engaged in a three-year dispute with the Rail, Maritime and Transport (RMT) union about guards on trains, which has resulted in industrial action.

The second worst performance on trust was by Great Northern with 24%, followed by South Western Rail and Thameslink, both on 27%.

All three of these scores were recorded in the autumn 2018 survey.

Great Northern and Thameslink services were crippled by the chaotic launch of new timetables in May 2018.

A spokesman for Govia Thameslink Railway, the parent company of Southern, Great Northern and Thameslink, said: "This report reflects the industry-wide issues surrounding the timetable changes last May.

"Passengers have been paid £17 million in additional industry compensation and we are now consulting the communities most affected on how we should invest a £15 million fund dedicated to improving their journeys.

"Punctuality and reliability are now firmly back on track, with record service levels on Southern, and we are running over 400 more services every weekday on the country's busiest network.

"We are working more closely with Network Rail to reduce the effects of infrastructure problems and have made some major improvements in communication to passengers at times of disruption."

RMT general secretary Mick Cash said: "For over three years RMT members have been warning that Southern is a basket case franchise, cutting corners on safety and service and not fit to run a railway.

"These latest shocking figures prove that we have been right all along."

The strongest trust performances were from Grand Central and Heathrow Express, who have consistently achieved scores of at least 70%.

Chiltern, Merseyrail and Virgin Trains all recorded ratings which did not dip below 60% over the four surveys.

Transport Focus submitted its analysis to the Government-commissioned Rail Review, which will make recommendations about the future of Britain's railway.

The watchdog's chief executive Anthony Smith said: "There are some wide variations between train operators that keenly reflect the passenger experience.

"Public trust in the railway is fragile but has never been more important. Building a good relationship with passengers will need to be a central part of any reform programme for the railway.

"Even small delays can damage passenger trust, so punctual services and accurate information are essential.

"New rules now require 'right time' reporting to the minute. This makes operators accountable for even the smallest delay and will be key to rebuilding public trust and winning future customers."

The Rail Review is being chaired by former British Airways chief executive Keith Williams. His inquiry will conclude in the autumn.