Clean-up teams are working against the clock to minimise the damage after crude oil gushed into the Evrona nature reserve in what is already one of Israel's worst environmental catastrophes.

Police have ruled out foul play after it was discovered the pipeline was breached during maintenance work as part of preparations for the international airport under construction in Timna. The Ministry said rehabilitation would take months, if not years.

The Ministry's "Green Police" are investigating the spill's cause, whether it could have been prevented and how it was handled once discovered. The company shut off the pipeline's valves, but the action was taken too late to prevent the spillage of millions of litres of oil.

Evrona is home to a large deer population and the northernmost douma palm trees in the world.

Ministry official Guy Samet said there was a 7km long "river of oil" flowing through the Evrona nature reserve in southern Israel - about 20km north of Eilat. He described it as "one of the gravest pollution events in the country's history" as fire fighters, Ministry officials, oil pipeline maintenance teams and police scrambled to the spill site to curtail the flow, close to two hours after the catastrophe occurred.

"Crude oil flowed throughout the reserve, causing serious damage ... to flora and fauna," Samet told Israel Radio on Thursday, estimating the spillage at millions of litres.

"Rehabilitation will take months, if not years. This is one of the State of Israel's gravest pollution events. We are still having trouble gauging the full extent of the contamination."

The pipeline links Eilat to the port city of Ashkelon and was opened in the 1960s to facilitate the movement of Iranian oil from the Persian Gulf to European markets. However, it has mostly been used to move oil and oil products from Eilat to different parts of Israel since the rupture in Israeli-Iranian relations in 1979.

While there was no damage on Jordan's side of the frontier, Jordanian news outlets reported large amounts of hydrogen sulphide were detected in the air around Aqaba, with some reports stating over 80 people were hospitalised with breathing difficulties after inhaling fumes.

Nature and Parks Authority Director General Shaul Goldstein said the body would examine the conduct of the oil pipeline company to determine if the spill was an accident or the result of negligence.