Labour unions and civil rights groups staged May Day rallies in several US cities on Labour Day yesterday to denounce President Donald Trump's get-tough policy on immigration, a crackdown they said preys on vulnerable workers in some of America's lowest-paying jobs.

Protests and marches challenging Trump's efforts at stepping up the deportation of illegal immigrants drew crowds by the thousands to the streets of New York, Washington, Los Angeles and San Francisco, with smaller gatherings popping up across the country.

A broad coalition of groups behind the events also took aim at various other Trump policies they saw as discriminatory or xenophobic, including his bid, so far blocked by the courts, to ban travellers from several Muslim countries and temporarily turn away all refugees.

But the primary impetus cited by civil liberties and labour activists was Trump's strict new immigration enforcement policy - falling most heavily on undocumented workers who toil in low-paying, non-unionised sectors such as fast-food, hospitality, child care and agriculture.

A May Day gathering grew unruly in Portland, Oregon, where a group of black-clad protesters roamed downtown streets in the late afternoon, setting fires, breaking storefront windows, throwing projectiles and vandalising a police cruiser.

Police, referring to the perpetrators as "anarchists", said they made three arrests.

Rallies elsewhere across the country were boisterous but mostly orderly, even festive.

In some cities, immigrant-run convenience stores and other businesses closed their doors in solidarity with the May Day rallies, and many protesters themselves gave up a day's wages to make their voices heard.

"Money will come back later, but not this opportunity, not this day," said David Anaya, 44, an illegal immigrant from Mexico, who chose to forfeit the US$300 he would have otherwise earned at his job as a welder.

He was one of thousands who gathered at MacArthur Park near downtown Los Angeles for what organisers called a show of "resistance, unity and defiance," then set off on an animated but peaceful march across town to City Hall.

A crowd of several thousand also assembled in Washington's Dupont Circle for a rally ahead of a planned procession to Lafayette Square, across the street from the White House.

'Not America any more'

Earlier in the day, 500 protesters marched through midtown Manhattan and rallied in front of offices of Wells Fargo and JPMorgan Chase & Co. Twelve were arrested, according to a spokesman for 'Make the Road New York', an immigrant advocacy group that claims 20,000 members.

The two banks were targeted because of their dealings with private companies that have built or manage some immigrant detention centres for the government, according to Jose Lopez, Make the Road New York's co-director of organising.

"The messaging for today was to stop financing immigrant detention facilities," Lopez said.

May Day, also known as International Workers' Day, has typically been a quieter affair in the United States than in Europe, where it is a public holiday in many countries.

May Day unrest flared yesterday in France and Turkey, where demonstrators clashed with police.

The US protests focused on Trump's crackdown on illegal immigration as he presses police agencies around the country to assist federal efforts at rounding up individuals sought for deportation and threatens to withhold federal dollars from "sanctuary cities" that do not cooperate.

Retired social worker Christina Reilly Vaccarino, 78, who emigrated from Ireland at age 15 with a green card allowing her to work as a nanny, said she was “disgusted” by Trump's policies on immigration, taxes and workers’ rights.

“I came to America at a time when everyone in Ireland believed that America is so wonderful, so great. And now, after all these years, to experience this? It’s not America any more," she said at an afternoon rally in Lower Manhattan.

Some Trump supporters said they would also turn out on May Day. Activist Joey Gibson said he and other conservatives would travel to Seattle to defend against what he described as communist and anti-fascist groups who have in the past faced off with police in the evening, after the conclusion of the usually peaceful daytime marches.

- Reuters