Rail passengers on some of the country's busiest commuter lines were urged today to make alternative arrangements on Friday and next Monday, as two further 24-hour strikes by train drivers were announced.

Hundreds of drivers at South West Trains (SWT), which operates out of London's Waterloo station, will walk out in a row over safety, causing travel chaos for tens of thousands of passengers across southern England and London.

Emergency timetables have been drawn up and were handed out to commuters at railway stations across the region today. Passengers have been warned there will be no trains at all on many routes, and only one in five services will run overall. Those that do run will start and finish earlier than usual.

"We therefore advise you to avoid the peak hours and to make alternative travel arrangements on these days if you possibly can," said SWT's operations director James Burt.

The company normally operates 1,700 services every weekday, and carries 400,000 passengers, including 350,000 into and out of Waterloo.

Talks between SWT and the drivers' union Aslef failed to break the deadlock yesterday. The union said it had put forward proposals it believed could resolve the dispute but an official said it was now a "pretty sure bet" that the strikes will go ahead as planned.

The dispute started over the use of taxis for a group of Waterloo-based drivers but escalated when SWT used managers to drive trains during a previous strike, prompting safety concerns at the union.

Last Tuesday, a 24-hour walkout by 900 drivers caused major disruption for commuters returning to work after the August bank holiday weekend.