A day after residents in Tel Aviv began to report a foul smell blanketing the city, officials said they were still unable to name the source of the odor, and did not want to speculate.

Officials believe the smell, which has been likened to chlorine, likely originated off the coast of southern Israel near Ashdod or Nitzanim. Residents as far north as Hadera reported smelling the odor.

A senior official at the Environmental Protection Ministry told Israel Radio on Friday that she could say with “almost certainty that the smell poses no danger to citizens.” Shuli Nezer, a senior vice-president at the ministry, said there should be much more data available by early next week.

“There’s no point in spreading hysteria,” Minister Gilad Erdan told Israel Radio Thursday afternoon. “There’s no danger.” He added that the ministry had launched a criminal investigation into the incident, but Nezer on Friday said that the ministry was waiting to determine who caused the incident before taking legal action.

Initial claims by the Home Front Command that the stench could have originated from a gas drilling site in the Nitzanim region were later disproven. The ministry also rejected a report by Channel 2 that a ground disinfection procedure at the Kfar Hayarok youth village, north of Tel Aviv, was its source.

The Environmental Protection Ministry carried out tests in the area to determine the composition of the smelly substance.