The strike by 1,400 union members, whose picket line chanting roused some hotel guests from their sleep, was the most aggressive step taken yet by the Unite Here union in this year's protracted contract disputes. Its members have authorized strikes in all three cities.

Mike Casey, the president of San Francisco Unite Here Local 2, said the walkout would last two weeks. It targets four of 14 hotels involved in on-again, off-again negotiations.

Casey described the action as a wake-up call to give the hotels a taste of operating without experienced staff. He added that he hoped it would encourage meaningful negotiations.

The threat of a multi-city work stoppage has provided the union with some leverage, as hoteliers and city officials fear that widespread strikes could discourage visitors and disrupt the industry's comeback from the 2001 recession and terrorist attacks.

Unite Here has emphasized the need to act in concert against an increasingly consolidated hotel industry on a range of issues, including lightening workloads and preserving healthcare coverage.

Meanwhile, the key stumbling block between labor and management is the union's demand for a two-year pact in all three cities. That would align contract expirations in nine cities and Hawaii, giving the union greater bargaining clout.

But Unite Here's national president for hospitality services, John Wilhelm, said Wednesday that the San Francisco local's decision to strike was made independently and did not portend a coordinated action.

"We have never said we intended to strike the hotels in all of the cities," Wilheim told reporters Wednesday morning. "The locals have the authority of their memberships to call a strike and are keeping their options open. Their goal is to do whatever is best for their members."

The struck hotels - the Argent, Hilton San Francisco, Crowne Plaza Union Square and Mark Hopkins Intercontinental - maintained operations using workers from hotels in other cities. Some guests crossed picket lines while others said they were checking out early.

Ed Portnoy, a doctor from Westlake Village, told the Associated Press that he and his wife and daughter had heard enough after being awakened by early-morning pickets.

"I don't know who's right or not," Portnoy said, "but it's not any way to spend a vacation."

About 4,000 union members work at the 14 hotels, but any eventual contract will affect about 8,000 workers at 60 San Francisco hotels.

"The actions of the union today have significantly escalated" the situation, said Barbara French, spokeswoman for the 14 San Francisco hotels, which are collectively known as the Multi-Employer Group.

French added that the group considered an action against even one of the hotels "an action against all."

The San Francisco hotels have a lockout agreement in which they would bar all union workers under certain circumstances. French said that there had been discussion of but no decision on a lockout.

She noted that the hotels were explaining the labor situation to guests and assuring them that service would not be compromised.

The nine hotels of the Los Angeles Hotel Employer's Council, which is handling negotiations with Unite Here Local 11, have their own joint lockout agreement, but there was no talk of invoking it Wednesday.

Local 11 President Maria Elena Durazo issued a statement supporting the San Francisco pickets but said there were no plans to strike. "We would like to get back to negotiations," she said. "We think there is plenty to talk about."

No new talks are planned. They were stopped indefinitely this month after federal mediator Peter Hurtgen, who was overseeing negotiations, left the country on previously scheduled business.

The Los Angeles hotels and Local 11 have filed unfair labor practice charges against each other with the National Labor Relations Board. The nine Los Angeles hotels are the Sheraton Universal, Westin Bonaventure, Westin Century Plaza, Hyatt Regency Los Angeles, Hyatt West Hollywood, Millennium Biltmore, Regent Beverly Wilshire, St. Regis and Wilshire Grand.

In Washington, talks are scheduled to resume next week between 14 hotels and Unite Here Local 25.