U.S. immigration officials are pushing for a change in policy to be allowed to prosecute parents caught crossing into the country illegally with their children, The Washington Postreported.

In a memo obtained by The Post, the officials say that threatening adults with criminal charges and prison time would be the “most effective” way to end illegal immigration.

But if enforced, the policy would also split up thousands of families. The memo does say parents who turn themselves in would not be prosecuted.

The current policy allows parents to be released and reunited with their children while they await civil deportation proceedings.

The memo sent to Homeland Security Secretary Kirstjen Nielsen on Monday was signed by acting Director of Immigration and Customs Enforcement Thomas Homan, Director of Citizenship and Immigration Services L. Francis Cissna and Customs and Border Protection Commissioner Kevin K. McAleenan, The Post reports.

The memo warned that the number of attempted crossings by parents with children will continue to rise if Nielsen does not act. It said nearly 700 attempts were made per day last week, the highest level since 2016.

It said the Trump administration tried this approach in the Border Patrol’s El Paso sector, which covers West Texas and New Mexico, between July 2017 and November 2017. As a result of that experiment, it said, the number of families trying to cross illegally fell 64 percent.

The Post quoted the memo as saying, “This decrease was attributed to the prosecution of adults. … Of note, the numbers began rising again after the initiative was paused.”