Andrés Manuel López Obrador has promised to fund a crackdown on migrants to Mexico from Central America with proceeds from the sale of his office’s aircraft, a 787 Dreamliner which has been on offer since shortly after the Mexican president took office in December.

Funds from the sale would be put toward the deployment of the newly formed national guard which has the power to detain migrants without correct papers, López Obrador said on Wednesday.

Under the deal struck on Friday, Mexico agreed to enforce the new measures to stop migrants crossing its territory in order to head off Donald Trump’s threat of imposing import tariffs of 5% on Mexican goods.

Mexico promised to send 6,000 members of the militarized national guard to seal its porous southern border with Guatemala – a major route for migrants fleeing violence, poverty and climate change.

López Obrador, also known as Amlo, insisted that the agreement had averted an economic and financial crisis and was “a good deal for our country”.

“About how much this plan is going to cost, let me say, we have the budget,” Amlo said at a daily news conference. “It would come out of what we’re going to receive from the sale of the luxurious presidential plane.”

Amlo said the starting price for the plane would be $150m. He expected the sale to close this week.

On Tuesday, the foreign minister, Marcelo Ebrard, said the immigration deal would be revisited in 45 days and a regional deal with countries in Central and South America would be sought if the migrant flows failed to slow.

But critics pointed out that the new national guard was initially presented as a force to fight organized crime and rein in Mexico’s soaring murder rate.

“Now they’re using this national guard not only to pacify the country, but for the detention of migrants,” said Alberto Xicoténcatl, director of the migrant shelter in the city of Saltillo. “It strikes us as a hypocritical discourse.”

Making good on his promise to rule with frugality and restraint, López Obrador regularly travels on commercial flights rather than the presidential plane, for which he said Mexico had paid up to 8bn pesos ($392m).

On Tuesday, El Universal newspaper reported that during the first three years of the preceding administration, 746 bottles of alcohol were consumed on the aircraft – including 35 bottles of booze which were opened on a short flight from Mexico City to Acapulco.

In contrast to his predecessor Enrique Peña Nieto, López Obrador has shown little interest in foreign travel, arguing there are too many problems at home. He has not left the country since taking office and has said he will skip the upcoming G20 conference in Japan.

“Mexicans associate presidential travel with waste,” said Rodolfo Soriano-Núñez, a sociologist in Mexico City.