Rail workers are "solidly " supporting a strike in a long running dispute over the role of conductors, crippling train services.

Members of the Rail, Maritime and Transport union on Southern Railway have walked out, causing fresh travel misery for passengers already suffering delays.

Southern services have been hit by staff shortages for weeks, leading to protests by travellers in Brighton.

Southern's owners, Govia Thameslink Railway, has blamed high levels of staff sickness for the recent disruption.

Delegates from the annual conference of Unison joined an RMT demonstration outside Brighton station.

RMT general secretary Mick Cash said from the picket line: "Our members on Southern are rock solid in support of the action this morning in the fight to stop the basket-case GTR franchise from ripping apart the safety culture on our railways in the drive for ever fatter profits.

"RMT is receiving brilliant support from passengers on the picket lines and social media who know only too well that this is a rail franchise in meltdown that has declared war on its customers and staff alike.

"The union knows that when Southern talks about 'changing the role of the guard' what they really mean is getting rid of the guard. We have no option but to strike to stop that lethal gamble being bulldozed through.

"We regret the inconvenience to passengers but our fight for jobs today is about protecting passengers' safety."

TUC deputy general secretary Paul Nowak said: "Nobody wants a strike. It means inconvenience for the public and lost pay for staff.

"The rail workers deserve our support. They are putting passenger safety first. Trains need more than just a driver - they need other properly trained staff to ensure that passengers are safe.

"If you're female, elderly, disabled or in any way vulnerable, having a guard on board makes a real difference. They are a helpful and reassuring presence, especially when things go wrong. That's the kind of human interaction that can't be automated.

"Southern Rail, backed by the Government, are putting their profits before passenger safety."

Southern said services are largely running to the revised strike day timetable.

Disruption will continue all day and is likely to affect some early morning services on Wednesday.

Between 6am and 9am, 90% of Southern services into London Bridge arrived on time, and 87.5% of services into London Victoria were on time, said the company.

A spokesman said: "The RMT has now accepted that jobs are not at risk, and the RSSB has nailed their bogus safety claims.

"Given this, passengers are bound to conclude that this strike is about nothing more than the RMT asserting their power to bring the railway to a standstill. Enough is enough, this strike should be the last."