A father and son who own hundreds of rental properties across Dallas have been accused in a lawsuit of keeping tenants in “unspeakably squalid conditions” while requiring them to pay for pest control.

In a complaint filed last week, tenants Joanna Pena and Sergio Rendon also claim that Hanna Khraish, his son Khraish H. Khraish and their company, HMK Ltd., are breaking state law by using a contract that fails to inform tenants about ways they can complain about defects in the rentals.

Khraish Khraish couldn’t be reached for comment Tuesday night, and his father hung up on a reporter.

“The defendants are the most prolific slumlords in Dallas County who operate a business which preys on the most vulnerable,” the lawsuit reads.

The Khraishes own single-family homes across the city, predominantly in West Dallas. Their portfolio includes about 450 low-income rentals, more than twice the number leased by another notorious landlord, Dennis Topletz. Topletz is also the target of a lawsuit accusing him of keeping tenants in properties riddled with code violations.

“Part of the problem is that by doing business illegally, they’re perpetuating a system where these tenants don’t even have the opportunity to understand that they have rights, that they’re not at the mercy of whatever the landlord is willing to dole out to them,” said attorney Michael Hindman, who along with Mark Ticer is representing tenants fighting the Khraish and Topletz businesses.

Hindman and Ticer point out that state law requires landlords to remedy or repair any condition in the property that affects “the physical health or safety” of a tenant. But the Khraishes’ tenants get no response when they complain about the lack of plumbing or heating, rats, missing doors, roofs with large holes and collapsed floors, according to the suit.

Many of the properties are valued between $10,000 and $20,000, yet the Khraishes file yearly lawsuits against the appraisal district to lessen their tax burden, the attorneys said in the complaint.

Hindman and Ticer are seeking class-action classification for the complaint, which they are also pursuing in their pending suit against Topletz.

The Khraishes were sued last year by a former apartment tenant who claimed to have been bitten in the foot by a rat while sleeping in one of their units. That case has not been resolved.

Meanwhile, Dallas officials have proposed revamping the city’s minimum housing standards to protect tenants from substandard rentals.