El Al said it and other airlines had temporarily suspended flights out of Israel early on Tuesday after a fuel delivery was found to be polluted.

The cause of the pollution was unclear. "We don't know, we are checking now," airline spokeswoman Liat Peleg said.

Israel Radio said thousands of passengers were stranded at the airport near the city of Tel Aviv.

The Israeli ports authority did not answer the telephone, nor was there comment from any other airlines that fly out of Israel.

"A standard check made on Monday evening by the Israeli fuel companies... showed that the fuel delivered to all airlines taking off from Ben Gurion Airport was polluted and does not meet international standards," Peleg said.

"The fuel companies therefore decided not to deliver fuel to flights taking off from Ben Gurion until clean fuel can be delivered. El Al flights as well as flights of other airlines will therefore be delayed," she said.

The company postponed at least six flights early on Tuesday and later made plans for some long-haul flights to take off and refuel in Cyprus or Turkey.

Asked whether authorities were investigating the possibility that the fuel was sabotaged, Peleg replied: "We are checking, we don't know."

The Haaretz daily newspaper said authorities suspected the fuel may have been mixed with water.