The much-vilified U.S. policy of separating children from parents who illegally cross the U.S.-Mexico border could continue under certain circumstances because of ambiguous language in President Donald Trump's order meant to end the practice, legal experts said.

"The first thing that hit me when I read the order was the tremendous amount of wiggle room built into it," said John Banzhaf, a professor or public interest law at George Washington University.

The order signed by Trump on Wednesday calls for those families to be detained together but it permits separation if deemed that detention with a parent "would pose a risk to the child's welfare." Family unity is the policy "where appropriate and consistent with law and available resources," the order said.