El Salvador's leader has made the extraordinary offer to jail Americans sent by their own country, Secretary of State Marco Rubio said on Monday.

It is uncommon for democratic countries to send their own citizens to serve prison sentences abroad.

But Rubio welcomed an offer to do just that by President Nayib Bukele, whose sweeping crackdown on crime has won him soaring popularity at home and hero status for many in President Donald Trump's orbit.

"He has offered to house in his jails dangerous American criminals in custody in our country, including those with US citizenship and legal residency," Rubio told reporters in San Salvador.

"No country's ever made an offer of friendship such as this," Rubio said.

"We are profoundly grateful. I spoke to President Trump about this earlier today," he said.

Rubio said that Bukele was also willing to take back Salvadoran citizens as well as nationals of other countries.

Rubio appeared to suggest that the prison transfer would focus on members of Latin American gangs, such as El Salvador's MS-13 and Venezuela's Tren de Aragua, who have acquired US citizenship.

"Any unlawful immigrant and illegal immigrant in the United States who is a dangerous criminal -- MS-13, Tren de Aragua, whatever it may be -- he has offered his jails," Rubio said.

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Since his return to the White House last month, Trump has put a top priority on speeding up the deportation of millions of people in the United States without legal status.

Trump has sought to crackdown on the right to birthright citizenship, which is enshrined in the US Constitution.

Trump has also unveiled plans to detain 30,000 migrants at the US base in Guantanamo Bay, Cuba -- a prison which previous Democratic presidents hoped to close.

Latin America's biggest jail

In a symbol of his anti-crime effort, a year ago Bukele opened Latin America's largest prison in an uninhabited area on the outskirts of Tecoluca, 75 kilometers (45 miles) southeast of San Salvador.

The prison, surrounded by huge concrete walls, is designed for 40,000 detainees, with around 15,000 estimated to be there now.

Bukele swept back to power last year with the public grateful for plunging crime in what was once one of the world's most violent countries — though some human rights groups have voiced criticism.

Rubio's motorcade traveled an hour through the forests to Bukele's lakeside vacation home on Lake Coatepeque, with the 43-year-old president sporting sunglasses and sneakers as he showed the top US diplomat the sweeping view.

As fans on a boat below cheered, Bukele waved down to them and told Rubio with a grin -- switching to English for a moment -- "Ninety percent approval rating!"

Bukele hinted at his prison offer as he met Rubio, telling reporters that the countries were working on a deal that goes beyond a 2019 accord on accepting migrants.

"I think it's much bigger and of greater scope than the agreement we did in 2019," Bukele said.

He said he was eager for strong relations with Trump, calling the United States "our largest partner, with which we must strengthen relations."

The Trump administration is especially eager to deport Venezuelans.

Since taking office last month, Trump has stripped roughly 600,000 Venezuelans of protection from deportation ordered by his predecessor Joe Biden, citing the economic and security crisis in the South American country run by Nicolas Maduro.

Ideological ally

The Trump administration has so far not touched the protected status from deportation for some 232,000 Salvadorans in the United States, which was also extended by Biden.

On the eve of Rubio's visit, Bukele unabashedly associated himself with Trump by backing his effort to dismantle US foreign assistance.

Posting on X in English, Bukele repeated talking points of Trump's billionaire friend Elon Musk by alleging that US assistance mostly goes to fund opposition groups, including non-governmental organizations.

El Salvador received some $138 million in US assistance during the 2023 fiscal year, led by support for the government and civil society and for basic education, according to official US data.

Guests at Bukele's second inauguration last year included the president's son Donald Trump Jr. and Tucker Carlson, a journalist close to Trump.