CAIRO (Reuters) - Egypt's Prime Minister Sherif Ismail said on Thursday that the search was underway to find the missing EgyptAir plane and it was too early to rule out any explanation for the incident, including terrorism.

"Search operations are ongoing at this time for the airplane in the area where it is believed to have lost contact," he told reporters at Cairo airport.

Asked by a journalist if he could rule out that terrorists were behind the incident, Ismail said: "We cannot exclude anything at this time or confirm anything. All the search operations must be concluded so we can know the cause."

Egyptian President Abdel Fattah al-Sisi will chair a national security council meeting on Thursday morning, a statement from his office said. It did not say if the meeting would discuss the plane.

(Reporting by Lin Noueihed and Mostafa Hashem)