Hundreds of Southern trains on some of London's busiest routes were cancelled today as staff began a 24-hour strike.

Members of the Rail, Maritime and Transport (RMT) union are staging a second day of industrial action in response to the company’s decision to transfer certain responsibilities from train conductors to drivers.

The walkout began just after midnight and is set to have a "significant effect" on services throughout the day, Southern warned.

It is the second 24-hour strike in the RMT's ongoing row with Southern over the operator's plans to abolish the conductor role and replace it with an "on-board supervisor", as well as moves to driver-only operated trains on some services.

RELATED: More strikes planned as talks between Southern and the RMT collapse over future of conductor roles

The union has accused the company of putting passengers' safety at risk and warned of job losses.

But Southern has denied the claims and accused the RMT of being "determined to inflict another day of misery" on commuters.

A spokesman for the company said: “The only thing that changes is the new conductors will no longer close the doors, a task that passes to the driver with the aid of CCTV. This will cost no-one their jobs, and frees up staff on board trains to better serve passengers."

Mick Cash, RMT General Secretary, said: “Our guards members on Southern are solid and determined this morning and the union welcomes the support from the travelling public as they recognise that this dispute is about defending safety critical jobs and services against the drive for cash-driven cuts that would see those services hacked to ribbons.

"With commuters paying thousands of pounds a year for their annual tickets on Southern there can be no explanation for the removal of the guards other than a central obsession in the board room for putting increased profits above public safety. That message is ringing out loud and clear as the dispute continues‎."

The union claims it is responding to the "threatening and abusive" stance the company has adopted by setting a deadline of May 20 for staff to sign up to plans to change the role of conductors.

The RMT has also accused the company of refusing to hold meaningful talks.

Are you affected by today's strike? Email daniel.omahony@newsquest.co.uk