The illegal immigrant controversy in the United States, which has reached a boiling point with massive protests nation-wide, is dividing Americans on how the problem should be resolved.

The issue was recently ignited by a controversial bill passed by Congress in December that would make it a felony to be an illegal immigrant.

The bill, passed mainly with Republican votes, targets an estimated 12 million people living illegally and without proper documentation in the U.S.

It calls for the three measures including: the deportation of all illegal immigrants, the construction of a massive fence along the Mexican-U.S. border and criminal repercussions for employers who hire them.

Experts say the impacts from the bill, however, would be far-reaching as the plan would cripple the economy, especially the agriculture and construction sectors where a large majority of illegal aliens are employed.

A recent study by the American Farm Bureau Federation said a crackdown on illegal immigrant labour could cause production losses in U.S. agriculture of $5 to $9 billion in the first one to three years, and up to $12 billion over four years or more.

A recent study by the Pew Hispanic Center, a nonpartisan "fact tank" in Washington whose mission is to improve the understanding of the U.S. Hispanic population and their impact, concludes Americans are increasingly concerned about immigration laws and split on how to handle illegal immigrants.

Some U.S. citizens feel immigrants are a burden, taking jobs and housing and putting a strain on the health-care system.

The study concludes a little more than the majority, 53 per cent, believe illegal immigrants should be deported, compared with 40 per cent who believe they should be granted some kind of legal status allowing them to live in the U.S.

On the overall effect of immigration, roughly as many citizens believe immigrants strengthen American society and the economy as those who feel immigrants threaten traditional American values.

Groups fighting for the illegal immigrants have staged massive rallies recently to pressure Congress, which has mid-term elections this fall, into granting an amnesty and eventual citizenship for the undocumented immigrants.

The illegal aliens say they want legislation that treats them fairly, humanely, and with respect.

Congress has proposed the building of a 1,123-kilometre wall along parts of the 3,219-kilometre Mexican border, where half the illegal immigrants are estimated to arrive from.

The Senate is stalled on a plan by U.S. President George Bush to revamp immigration laws and create a temporary worker program, which would open the way for more than 7 million illegal immigrants to become U.S. citizens.

The initiative would allow immigrants to remain in the U.S. for a fixed amount of time, based on the condition they would eventually go home.

Bush insists it is a legal way of filling "the jobs Americans don't want," however, the plan has put him at odds with many in his own Republican Party.

Labour groups are wary of a guest worker program that does not provide a path to permanent residency, saying it would create an underclass of workers.

Critics say the plan would lead to even more illegal immigration.

Many big businesses, saying they recognize that illegal immigrants sustain the U.S. economy, shut down operations on May 1 during nation-wide protests called "A Day Without Immigrants."

The protests, which were to be attended by tens of millions, included job walkouts, students skipping classes and instructions for illegal immigrants to not buy anything as a way to boycott American business.

In California, which has more undocumented workers than any other state with an estimated 2.75 million, the State Senate endorsed the day of action and described it as a way to educate Americans about the "tremendous" contribution immigrants make on a daily basis to society and the economy.

Critics of the mass rallies and protests say the demonstrations are blackmail and only harden the public opinion against illegal aliens.

Some illegal immigrants planned to stay out of the public spotlight, however, after rumours swirled that federal officials were planning on hunting immigrants during the protests. It led to empty classrooms, work sites and shopping areas across the U.S.

Federal officials recently arrested more than 1,100 immigrant employees and seven managers at 40 sites of IFCO Systems, which makes crates and pallets.

Homeland Security Secretary Michael Chertoff said he plans to step up workplace enforcement of immigration laws.

U.S. conservatives and political analysts who support the deportation of immigrants say the security measure is needed, especially after the Sept. 11, 2001 terrorist attacks.

It's not yet known how Canada will be affected by the proposed immigrant crackdown.

A spokesman for the Canadian embassy in Washington says Canada will have to continue to prove to U.S. lawmakers there is much better security on the northern border and a stronger, more committed effort from both sides.

Some facts about illegal immigrants:

• The pace of unauthorized arrivals to the U.S. has accelerated over the last 20 years. On average, nearly five times as many illegal immigrants enter the country each year now as they did in the 1980s;
• About 40 per cent have been in the U.S. five years or less;
• 75 per cent were born in Latin America;
• Most enter by crossing the Mexico-U.S. border; and
• California (2.75 million), Texas (1.6 million) and Florida (just under a million) host the most illegal immigrants.