Armed gangs patrol a street in Haiti. [Courtesy]

As violence continued in the Haitian capital of Port-au-Prince, a powerful gang leader on Thursday threatened political leaders who are set to take part in a planned transitional council to govern the Caribbean nation.

Under pressure from the United States, unpopular and unelected Prime Minister Ariel Henry announced Monday that he would step down once the transitional council was in place. The White House confirmed Thursday that Henry is in Puerto Rico.

The calm following Henry's announcement eventually gave way to a resurgence of violence late Wednesday, including a shootout in one neighborhood of the capital and an attack on a police academy on Thursday. Haitian authorities have expanded a nighttime curfew until Sunday.

In a seven-minute audio message that was shared widely on the WhatsApp platform Thursday, gang alliance leader Jimmy "Barbecue" Cherizier threatened the politicians who are to take part in the transitional council.

"Don't you have any shame?" Cherizier said, directing his remarks at politicians who he said were looking to join the council. "You have taken the country where it is today. You have no idea what will happen.

"I'll know if your kids are in Haiti, if your wives are in Haiti ... if your husbands are in Haiti," he said in an apparent threat to their families. "If you're going to run the country, all your family ought to be there."

"We are going to continue the fight for Haiti's liberation," Cherizier, a former policeman, told the Spanish-language network W Radio.

On Thursday, the United Nations said it was working to establish an aid airlift to Haiti.

"It's bringing in some supplies. It's also taking some U.N. staff out and bringing other U.N. staff in," the secretary-general's spokesperson, Stephane Dujarric, said.

U.S. Secretary of State Antony Blinken told reporters on Wednesday that he had spoken with Kenyan President William Ruto, whose country is expected to lead an international security mission to Haiti to help restore order.

"I was on the phone this morning with President Ruto of Kenya, who confirmed Kenya's preparedness to lead that mission, as soon as the new council is stood up, which we believe will happen in the next couple of days, and an interim prime minister is selected. That mission can move forward," Blinken said.

In Washington, the U.S. Senate voted on Thursday to confirm career diplomat Dennis Hankins as ambassador to Haiti. The diplomatic post has not been filled in the country in almost 2-1/2 years.

The U.S. said that its embassy remained open and that limited operations were continuing, focused on assisting Americans in Haiti and "supporting Haitian-led efforts to secure a peaceful transition of power."

Other embassies, including Canada's, have similarly reduced embassy staff in the country over safety concerns.

The United Kingdom, meanwhile, said it would increase security in the nearby Turks and Caicos Islands, which are a British Overseas Territory.