Trump to spare US 'dreamer' immigrants from crackdown

Many of the instructions will not be implemented immediately because they depend on Congress, a public comment period or negotiations with other nations, the officials said. Mexican immigration officials immediately objected to part of the new rules.

The guidance also calls for the hiring of 10,000 more US Immigration and Customs (ICE) agents and 5,000 more US Customs and Border Protection (CBP) agents.

The DHS will need to publish a notice in the Federal Register subject to review in order to implement one part of the plan that calls on ICE agents to increase the number of immigrants who are not given a hearing before being deported.

The new rules would subject immigrants who cannot show they have been in the country for more than two years to "expedited removal." Currently, only migrants apprehended near the border who cannot show they have been in the country more than 14 days are subject to rapid removal.

The memos also instruct ICE to detain migrants who are awaiting a court decision on whether they will be deported or granted relief, such as asylum. DHS officials said they are reviewing what jurisdictions may have laws in place that prevent the amount of time immigrants can be held.

The agency also plans to send non-Mexican migrants crossing the southern US border back into Mexico as they await a decision on their case. The DHS officials said this plan would be dependent on partnerships with the Mexican government and would not be implemented overnight.

An official with Mexico's immigration department said it is "impossible for the United States to send deported or repatriated Central Americans to Mexico" because of existing treaties between the United States and Mexico.

The guidelines were released a day before US Secretary of State Rex Tillerson and Homeland Security Secretary John Kelly were due in Mexico City for talks with President Enrique Pena Nieto and Mexican officials.