The strapped city has already expanded its controversial migrant complex on Randall’s Island’s youth soccer fields to house 3,000 people — 50% more than expected — before asylum seekers even moved in Sunday.

The site, which will now consist of five dormitory-style tents, began housing the first wave of migrants there in the afternoon, with about 150 single men expected before the end of the day, city officials said.

“This isn’t the solution for the next two, three, four months — this is giving us a little breathing room for the next few days, really,” warned Christina Farrell, the city’s first deputy commissioner of Emergency Management, to reporters during a tour Sunday.

Each air-conditioned sleeping tent will house 600 green and black cots, while a dining tent featuring long white tables will offer three meals a day.

The dining center will stay open 24/7 to also provide ’round-the-clock drinks and snacks, and laundry service and individual lock boxes will be offered, too.

There are separate bathroom cabins and an intake area.

Authorities initially said the facility would house 2,000 migrants, but that figure was upped to 3,000, officials revealed Sunday — a the city groans under its massive migrant influx.

“There are a lot of misconceptions and misinformation about facilities such as these,” Immigrant Affairs Commissioner Manuel Castro told reporters. “But as you can see, these facilities are well-constructed.

“They have quite ample space for migrants, asylum seekers, to congregate and spread out, too.”

The first bus of single men pulled up to Randall’s Island at 1:53 p.m.

“I’m feeling good,” said Rafael Bracho, a 29-year-old Venezuelan immigrant who said he’s been in the city for six months. “The government of the United States of America, they help you.”

Ted Long, senior vice present of NYC Health/Hospitals, said there will be 24/7 security at the site.

“As everybody knows with the number of asylum seekers crossing our borders into our country each day, we are seeing the numbers go down,” Long said. “However, in New York City we are seeing the number of asylum seekers every day go up.

“So because of that, this facility could be full fairly soon,” he said.

Farrell said the men being moved in Sunday were selected from among the thousands of migrants being housed by the city.

“We have different populations,” she said. “We have adult families, single women and single men. Since we are starting with single men, we looked at our different facilities and who has been at our sites the longest. And so these are the people we are moving in today.”

The massive complex is being funded by state taxpayers, who will shell out $20 million a month to keep it up and running, Gov. Kathy Hochul said earlier this month.

It is one of four state-funded migrant sites, with Hochul’s plan to add Brooklyn’s Floyd Bennett Field, a former US military airfield, fizzling after White House officials backed off on approving the plan.

The Randall’s Island site, erected over recreational soccer fields, is the latest mega-shelter set up to handle the unprecedented influx of migrants from the US border with Mexico since last spring.

One of Mayor Eric Adams’ own top commissioners has spoken out against using the fields.

Vilda Vera Mayuga, head of the city’s Department of Consumer and Worker Protection, circulated petitions to block the use of youth soccer fields for the mega-shelter facility.

Adams said some 100,000 asylum seekers have been bused into the Big Apple from border states, with the city now housing nearly 60,000 of them — while others were bused to upstate hotels.

Adams has estimated that the migrant crisis could cost the city $12 billion over three years.

Hochul and Adams have repeatedly sought more help from President Joe Biden to handle the crisis.