ICE raids have already started in California, ahead of plans to round up thousands of immigrants across the U.S. this weekend, according to a group of lawyers.

Attorneys from the Bay Area of San Francisco have claimed the raids are underway and began in Contra Costa County this past Sunday.

They also claimed that ICE was refusing to let detainees know they can have access to legal help, reports KRON4.

On Sunday authorities will begin arresting at least 2,000 immigrant families eligible for deportation in a nationwide series of raids long threatened by President Trump.

Attorneys from the Bay Area of San Francisco have claimed ICE raids began in Contra Costa County this past Sunday, a week before they are planned to start (file picture)

Several politicians including House Speaker Nancy Pelosi have spoken out about the raids informing immigrants they don't have to answer the door unless ICE officials can show them a valid warrant.

Yesterday the group of Bay Area attorneys went to the federal ICE offices in San Francisco to demand information about the threat of raids this weekend.

Attorney Siobhan Waldron said: 'ICE is not only targeting those without immigration status, but those with status, so everyone must must educate themselves.

She explained how ICE cannot come into a house without a warrant signed by a judge and said they 'almost never' have this.

On Sunday authorities will begin arresting at least 2,000 immigrant families eligible for deportation in a nationwide series of raids (file picture)

'An ICE deportation warrant is not the same as a search warrant,' said House Speaker Nancy Pelosi in a notice to immigrants who may be subject to ICE deportation raids beginning Sunday

Ms Waldron said 'do not open the door' before adding: 'There is a history of prohibiting attorney access here in San Francisco and at a new facility in Stockton.'

Trump forewarned of the operation in June, but it was delayed partly because of disagreements within the administration, the New York Times reported on Thursday.

The paper revealed that ICE has obtained court orders for the removal of about one million undocumented migrants, according to a senior administration official, but the initial raids will target some 2,000 across at least 10 cities.

Immigrant advocates said the advance word of the raids could enable at least some of those targeted to evade arrest.

The operation would target some 2,000 families whose immigration cases had been expedited in a special court docket and resulted in deportation orders.

People rally in June in Los Angeles against a Trump administration plan for the Immigration and Customs Enforcment agency to use an Oklahoma military base as a detention center for detained migrant children

IN THE CARDS: Pelosi read from a card with information about how to handle ICE raids

By comparison, ICE typically detains about 12,000 people per month, not including Border Patrol arrests near the border.

'Two thousand people deported is not that large in the annual scheme of things,' said Stephen Yale-Loehr, a Cornell Law School professor specializing in immigration.

He pointed out that the administration of former President Barack Obama deported more than 400,000 people a year during his first term.

'On the other hand the mere fact that they are announcing these raids is sending fear among immigrants and is causing them to hide or take other actions,' he said.

The threatened arrests come after apprehensions of migrants on the southwest border hit a 13-year high in May before easing in June as Mexico increased immigration enforcement.

Planning for the operation was rapidly changing, and final details were in flux, the New York Times reported.

ICE agents will carry out the operation over several days starting Sunday July 14, the newspaper reported, citing unnamed sources including two current and one former homeland security officials.

Officials told the paper that when possible, immigrant families placed under arrest will stay together in family detention centers in Texas and Pennsylvania.

Hillary Clinton urged Twitter followers to share Spanish-language guidance ahead of the raids

While some might stay in hotel rooms because of space constraints until travel papers are arranged.

The plan would also allow for the possible detention and deportation of people who were not specifically targeted.

U.S. House of Representatives Speaker Nancy Pelosi, the top elected Democrat in the United States, called the operation 'heartless'.

She said she was hoping that Hispanic evangelicals who helped Trump get elected in 2016 would appeal to him to call off the arrests.

'If ICE agents don't have a warrant signed by a judge, a person may refuse to open the door and let them in,' Pelosi said at her weekly news conference in the U.S. Capitol, noting that even undocumented immigrants have rights under U.S. law.

People were urged to remain silent, get a lawyer, and take videos during the planned raids which are said to start on Sunday

Former Secretary of State Hillary Clinton also weighted in on Twitter, urging people to share Spanish-language guidelines such as 'toma fotos y videos' – meaning take photos and videos.

'Por favor comparte,' Clinton wrote, or please share.

They were taking a cue from Rep. Alexandria Ocasio-Cortez also urged people to 'know your rights.'

'Check your neighbors & know your rights,' she tweeted earlier Thursday.

'Remember: no one can enter your home without a *judicial warrant.*' she advised. She also wrote that 'Sometimes ICE will try to show other papers to get in your house. Judicial warrants are from a court.'