Mexico's leftist President Andres Manuel Lopez Obrador said he spoke by telephone Wednesday with U.S. President Donald Trump about migration and job creation.

The issue came to the fore last month when a caravan of about 7,000 migrants arrived in the border city of Tijuana and some attempted to enter the United States.

"In respectful and friendly terms, we spoke about the migration issue and the possibility of implementing a joint program of development and job creation in Central America and our country," Lopez Obrador wrote in his Twitter account.

The Mexican president has called on the United States to join in a "Marshall Plan" effort to commit about $20 billion in public and private investment in Central America to create jobs, so people there won't have to emigrate.

Despite their differences in background and policy, the relationship between the two leaders has been quite cordial. Lopez Obrador, who took office Dec. 1, has said he hopes to make migration a choice, not a necessity, for poor people of the region.

Earlier Wednesday, Mexico's top security official said the government will close off illegal entries at its southern border with Guatemala, but didn't say exactly how the country plans to accomplish that daunting task.

Interior Secretary Olga Sanchez Cordero said the new administration will end the practice of undocumented or illegal crossings over the Suchiate River, which marks much of the border between Mexico and Guatemala.

"In the south there will be only one entry, on the bridge," she said. "Anyone who wants to enter illegally, we are going to say: 'Get in line and you can enter our country.'"

Sanchez Cordero offered no details on how that would be done, however.

In late October, Mexican authorities briefly tried to block a migrant caravan from crossing the river with ranks of police and military personnel, a helicopter and boats but the migrants crossed anyway.

Sanchez Cordero said the migrant caravan that crossed the southern border in October "is no longer an issue."

"Do you know why it is no longer an issue? Because in five days this administration solved the issue, five days," she said, referring to the first week since Lopez Obrador took office. "The United States was impressed."

The new administration has mobilized material and equipment to improve conditions at the migrants' shelter in the northern border city of Tijuana, but problems continue because the Central American there are frustrated by the slow pace at which U.S. officials are processing asylum requests.

Sanchez Cordero said Mexico will promote a "Christmas at Home" campaign to encourage many of the migrants to return to their home countries for the holidays.