Los Angeles, May 2 (IANS) Thousands of people were assembling in downtown Los Angeles early Sunday for a May Day rally intended to press for the liberalisation of immigration laws.

Spurred by the new Arizona immigration law, which makes it a crime to stay in the country illegally, about 100,000 people were expected to take part in the rally, Xinhua reported citing the organisers.

"It is estimated that masses of workers will take to the streets in over 70 cities nationally to not only decry the horrible legislative act in Arizona, but to demand a fair and humane immigration reform by this Democratic administration in 2010," said Nativo Lopez, president of the Mexican American Political Association and an organizer of the rally.

Arizona's law "only gives working people, immigrants, youth, women, trade unionists and their sympathizers more reason to march", said Lopez.

The immigration law signed by Arizona Governor Jan Brewer last Friday requires police officers to determine a person's immigration status when there is reasonable suspicion that the person was living illegally in the country.

The law is to take effect this summer, 90 days after the state's Legislature adjourns.

Rally organisers have been urging people to attend Saturday's May Day march as a show of opposition to the Arizona law.

Los Angeles Mayor Antonio Villaraigosa said he planned to join the marchers.

Calling the Arizona law "unpatriotic and un-American", Villaraigosa said: "While we recognise that we must enact 21st century legislation to secure our borders and ensure the safety of all our citizens, the law signed by the governor of Arizona simply does not do this."

"The Arizona law is not only misguided, it is unpatriotic and unconstitutional ... I add my voice in strongly opposing this unpatriotic and un-American law. And I call upon our federal leaders to pass comprehensive immigration reform in its place. Because in the US that my grandpa came to 100 years ago, no person should be treated differently in the eyes of the law.

"In the US, no victim should live in fear of reporting a crime because of their immigration status, and in the US, no one should be afraid to walk down the street because of the colour of their skin," the mayor added.

Los Angeles Police Department Chief Charlie Beck said he expected the march to be peaceful.

"I'm looking forward to a May Day where people get to come together, exercise their right to freedom of speech, get their points across and where America can see how a community comes together in a city in a peaceful manner with its police department," Beck said.

Beck also said he did not support the Arizona law, saying the Los Angeles Police Department's Special Order 40 -- which prevents officers from contacting people solely to verify if they are legal residents -- has worked effectively for more than three decades.

"It is the mandate of this police department that we do not initiate police activity due to immigration status," Beck said.