Updated

By David Schwartz and Tim Gaynor

PHOENIX (Reuters) - Immigration rights activists called on baseball fans on Tuesday to stay home from Arizona Diamondbacks games as part of a broad economic boycott to protest a statewide crackdown on illegal immigration signed into law in Arizona.

As a backlash by Hispanic groups, organized labor and civil liberties activists gained steam, the leader of the California Senate and officials in two of the state's biggest cities also moved to cut ties with companies based in neighboring Arizona.

Opponents of the state immigration law, the toughest on the books in the United States, urged travelers to avoid the tourism-dependent Grand Canyon state and for business groups and other organizations to hold their conventions elsewhere.

The Arizona Hotel and Lodging Association said six organizations had canceled conventions in the state, including the 11,000-member Immigration Lawyers Association, which had planned to hold its annual fall meeting in Scottsdale.

"There is widespread indignation not only in Arizona but throughout the country, and where people are under siege, they will look for ways to fight back," said Pablo Alvarado, executive director of the National Day Laborer Organizing Network.

The furor was sparked on Friday when Arizona Governor Jan Brewer signed into law a controversial measure designed by Republican sponsors to drive the state's illegal immigrants, the majority of them from Mexico, back to their home country.

Slated to take effect 90 days after the current session of the state legislature adjourns, the statute requires state and local police to determine a person's immigration status if there is "reasonable suspicion" that they are undocumented -- a mandate that critics say opens the door to racial profiling.

Opponents charge the measure amounts to an unconstitutional infringement on the exclusive authority of the federal government to control immigration, and a court challenge to the measure is widely expected.

Enactment of the measure has spurred a renewed push on President Barack Obama to make good on his campaign promise to press for comprehensive federal immigration reform. His administration said on Tuesday it was considering a court challenge to the new law.

But Arizona's Major League Baseball team, the Diamondbacks, became the first high-profile target of immigrant rights activists seeking to roll back the Arizona law, known as Senate Bill 1070.

BASEBALL 'AMBASSADORS' TARGETED

"The Diamondbacks are like ambassadors from Arizona to the rest of the country, and the world for that matter, and we want fans to stay away until the law is rescinded or neutralized," said Tony Herrera, an activist with a national group calling itself the Great Arizona Boycott 2010.

Herrera said his group is urging fans to refrain not only from going to Diamondback games, but also from buying the club's T-shirts and other merchandise. He said activists would form picket lines to pressure fans not to attend a game in Chicago against the Cubs scheduled for Thursday.

The Diamondbacks had no immediate comment on Tuesday.

Arizona is home to an estimated 460,000 of some 10.8 million illegal immigrants in the United States and form the backbone of a shadow labor force that works in industries ranging from construction and agriculture to restaurants and child care.

Calls for an Arizona boycott spread beyond the state.

On Tuesday, California Senate President Pro Tem Darrell Steinberg, a Democrat, called on Governor Arnold Schwarzenegger to do everything "legally possible" to sever the state's economic ties with Arizona.

In Los Angeles, a city councilwoman introduced a resolution calling for America's second-largest city to end all contracts with Arizona-based companies and "stop doing business with the state." It followed similar calls by San Francisco City Attorney Dennis Herrera on Monday.

Some Arizona Democrats who opposed the immigration crackdown nevertheless are uncomfortable with the boycott and said their state as whole should not be punished.

The call was taken up on social networking site Facebook, where one group said any such move "unfairly targeted" 200,000 hotel workers in the state.

(Additional reporting by Steve Gorman and Dan Whitcomb in Los Angeles, and Peter Henderson in San Francisco; Editing by Mary Milliken and Cynthia Osterman)