Utility workers inspecting one of the New York City buildings which were destroyed in a suspected gas explosion earlier this week found dangerous gas line connections that created a "hazardous situation," a Con Edison spokesman said on Saturday.

Spokesman Allan Drury said that workers inspecting the building on Aug. 6, 2014, found leaks in hoses that were part of the building's gas infrastructure, and that Con Edison shut off the building's gas for about 10 days, until it was determined to be safe, Reuters reported.

New York Mayor Bill De Blasio said Friday that the explosion -- which injured 22 people, four critically, and has left two people still missing -- could have been the result of someone having “inappropriately accessed”, one of the building's gas lines.

Hyeonil Kim, the owner of a Sushi restaurant that was destroyed in the blast, told the New York Times that Con Edison employees informed him that gas intended for his premises was being siphoned off -- so-called illegal gas tapping -- for use in the newly renovated apartments upstairs in the five-story building.

Meanwhile, the search for missing persons who may be trapped in the rubble continues, with emergency services workers using dogs and removing debris by hand in a bid to locate any victims.

Authorities conceded, however, that the chances of finding anyone in the wreckage of the buildings was slim. When asked about whether anyone in the buildings would have survived the explosion, city Emergency Management Commissioner Joseph Esposito told the Associated Press: “I would doubt that very seriously.”

Emergency services personnel estimated that it could take up to a week to complete the search, the agency added.

Investigators are reportedly working to determine if modifications to the building's gas system carried out by a private contractor were what caused the explosion.

Contractor Dilber Kukic, who multiple agencies have named as the having carried out work that was inspected shortly before the blast which was found to be unsatisfactory, is currently in hospital after being injured in the explosion.