(Reuters) - A plan by U.S. protesters against illegal immigration to block traffic at more than a dozen border crossings in the southwest on Saturday was canceled after organizers said they received online threats from Mexican drug cartels.

Billed as a "Shut Down All Ports Of Entry" protest against the Obama administration's immigration policies, demonstrators had said they would try to stop incoming and outgoing traffic at 17 locations in Texas, New Mexico, Arizona and California.

But lead organizer Stasyi Barth posted a warning on the event's official website saying that a combination of violent threats and "suspicious activity" on the group's Facebook page prompted her to call off the action.

"If you attend, you are not just putting yourself in danger, but the law enforcement officers, as well," Barth wrote. "Risking anyone's life is not worth it!"

Another organizer, Rob Chupp, said the threats came from Mexican drug cartels, but did not elaborate. He said that while the protest was officially canceled, he and some others still planned to demonstrate in Brownsville, Texas.

U.S. Customs and Border Protection said in a statement on Friday it has been coordinating with local police departments to respond to any situation near the ports of entry.