PHOENIX (Reuters) - Arizona lawmakers passed a controversial immigration bill on Monday requiring police in the state that borders Mexico to determine if people are in the United States illegally, a measure critics say is open to racial profiling.

Lawmakers in the Arizona Senate voted 17 to 11 to approve the bill, widely regarded as the toughest measure yet taken by any U.S. state to curb illegal immigration.

The state’s House of Representatives approved the measure last week. Governor Jan Brewer, a Republican, has five days to veto the bill or sign it into law.

Immigration is a bitterly fought issue in the United States, where some 10.8 million illegal immigrants live and work in the shadows, although it has been eclipsed in recent months by a healthcare overhaul and concern over the economy.

The law requires state and local police to determine the status of people if there is “reasonable suspicion” that they are illegal immigrants and to arrest people who are unable to provide documentation proving they are in the country legally.

It also makes it a crime to transport someone who is an illegal immigrant and to hire day laborers off the street.

“I believe handcuffs are a wonderful tool when they’re on the right people,” said Russell Pearce, the Republican state senator who wrote the bill.

We want to “get them off law enforcement and get them on the bad guys,” he told Reuters.

Opponents of the Arizona law, some of whom held a vigil outside Brewer’s home on Monday to urge her to veto the measure, say it is unconstitutional and would discriminate against Latinos.

“You cannot tell if a person walking on a sidewalk is undocumented or not ... (so) this is a mandate for racial profiling,” said Pablo Alvarado, director of the National Day Laborer Organizing Network.

Alvarado said his group would call on the federal government to intervene and was considering legal action to overturn the bill.