A sprawling homeless complex on Wards Island that houses gang members, parolees and sex offenders has gaping holes in the perimeter fence that are being used to sneak in weapons, drugs and even women, The Post has learned.

The city-funded Help USA ­facility, home to about 250 men, has an NYPD-managed access control point that is supposed to screen for any contraband.

But the security is pointless given the gaps in the fence that provide easy access to the ­unmanned rear of the facility, sources said.

Help USA has known about the holes for a year and a half and done nothing about them, said a representative for Teamsters 237, the union that represents many Department of Homeless Services workers.

One space in the sagging fence surrounds an FDNY driving course behind the shelter, and includes a makeshift plywood door that’s large enough to fit an adult.

It sits near the Wards Island footbridge — a publicly accessible pedestrian crossing into Manhattan that is open 24 hours a day.

Less than 200 feet away, a second hole leads directly to the back doors of five shelter buildings, the first only about 10 feet away. Cigarette butts and discarded beer cans litter the area.

Shelter staffers said they’ve received multiple complaints of women coming in and out of the complex via the fence.

“Apparently the shelters are the new hot spots and the new sex clubs,” said a source who patrols the shelter.

At the end of June, a woman was caught in a resident’s bed, booted from the facility and charged with trespassing.

Police sources and the union rep believe the holes in the fence are also a gateway for drugs and weapons.

Late Wednesday, The Post observed nearly a dozen men, all carrying bags, passing through one of the holes on their way to and from the footbridge. One was using an iPhone flashlight to navigate.

“Anything you could imagine could be in that shelter, and it would get in without a trace. No one would even know until it’s too late,” a source said.

A dagger with a brass-knuckle handle was recently discovered and drugs and weapons are confiscated on a daily basis, multiple sources said.

The Parks Department and Help USA pointed fingers at each other over who is responsible for repairing the fence.

“The health, safety, and security of our clients is our number one priority, and we are resolving this matter as we speak,” the Department of Homeless Services said. “We do not tolerate illicit substances or contraband in our shelters and thanks to the NYPD Management Team, shelters are experiencing better policing, increased monitoring, and improved data, resulting in more effective reporting and enforcement.”

Additional reporting by ­Kenneth Garger