"Biggest part of deal with Mexico has not yet been revealed!" Trump tweeted (File)

U.S. President Donald Trump on Tuesday stood by his comments that part of the migrant deal with Mexico announced over the weekend had yet to be made public, even after Mexican officials unveiled new details of the agreement.

"Biggest part of deal with Mexico has not yet been revealed!" Trump tweeted without giving further details.

Asked about what other side deals could be in the latest deal, White House spokeswoman Sarah Sanders declined to comment, saying she did not want to get ahead of Trump or Mexican President Andres Manuel Lopez Obrador in making any announcements.

Instead, Sanders told Fox News in an interview that Mexican officials had said "further action could be announced and that we will continue those discussions."

On Monday, Trump also said Mexico would soon disclose part of the agreement with no details other than saying that portion would have to be taken up by the Mexican Congress.

Announcing previously undisclosed details of Friday's deal, Mexican officials said on Monday they had 45 days to show that increased enforcement efforts were effective in reducing flows of migrants. If not, they would have to talk with the United States about additional measures.

The United States wants Mexico to be declared a safe third country in which asylum seekers would have to seek safe harbor instead of the United States, a demand Mexico had long rejected.

Mexican Foreign Minister Marcelo Ebrard dropped his previous opposition to that idea in comments on Monday, but said any such arrangement should share the asylum load with other Latin American countries.

He said these measures would have to be taken up with the Mexican Senate.

"If we don't have results on what we're doing (in 45 days), we'll start conversations on what they want," Ebrard said.

The deal struck on Friday averted import tariffs on all Mexican goods, which Trump had vowed to impose unless Mexico did more to curb migration.