SAN FRANCISCO (Reuters) - Union workers at the San Francisco Bay Area's BART commuter rail system went on strike early Monday morning, setting the stage for transport chaos across much of the region.

The strike by 2,400 BART workers came after acrimonious negotiations centered on wage and benefit issues broke down late Sunday, just hours before current labor agreements expired. Both sides blamed the other for abandoning the talks.

BART serves about 400,000 riders daily, many of whom rely on the system to travel from Oakland, Berkeley and other communities on the east side of San Francisco Bay into the city of San Francisco.

The strike will shut down the system once all trains are parked early Monday morning and is expected to bring widespread travel disruptions and traffic gridlock.

Local officials are adding extra ferry service and BART plans to run a small number of special buses, but those measures will serve only a fraction of regular BART riders.

"It's not going to be fun for anyone," said John Goodwin, a spokesman for the regional Metropolitan Transportation Commission.

The BART unions have demanded significant pay rises, while management has sought increased pension and healthcare contributions. Union negotiators say safety protocols have also been an issue.

The two sides remained far apart through months of negotiations, and talks broke down repeatedly before resuming Sunday afternoon at the behest of Governor Jerry Brown.

A BART spokesman said the agency had put forward a "fair and responsible" offer that included an 8 percent pay increase over four years, but union negotiators rejected the proposal and contended that management was not negotiating in good faith.

BART workers last went on strike in 1997, and were on picket lines for six days before a contract agreement was reached.

Union leaders were subdued as they announced the strike at a midnight press briefing.

"Tonight we are going to be going on strike, we will make sure everyone gets home safe and all the trains are put to bed before we go out," said Rhea Davis, vice president of a Service Employees International Union unit that represents BART workers.

"I pledge that we will do the best we can to come to a quick resolution and get the Bay Area moving."

(Reporting by Jonathan Weber and Noel Randewich; Editing by Alistair Lyon)

[Image: El Cerrito Del Norte BART Station, via Wikipedia Commons]