An EgyptAir jet carrying 66 passengers and crew from Paris to Cairo disappeared from radar over the Mediterranean south of Greece on Thursday, with Athens saying the plane swerved in mid-air before plunging from cruising height and vanishing.

Egyptian Prime Minister Sherif Ismail said it was too early to rule out any explanation, including an attack like the one blamed for bringing down a Russian airliner over Egypt’s Sinai Peninsula last year.

The country’s aviation minister said a terrorist attack was more likely than a technical failure.

Greece deployed aircraft and a frigate to search for the missing Airbus and officials said they had found pieces of plastic and two lifevests that appeared to have come from an aircraft in the sea 230 miles (370 km) south of Crete.

Egypt said it would lead the investigation and that France would participate. Other countries also offered to help, including Britain and the United States.

In Washington, President Barack Obama received a briefing on the disappearance from his adviser for homeland security and counter-terrorism, the White House said.

Greek Defence Minister Panos Kammenos said the Airbus had first swerved 90 degrees to the left, then spun through 360 degrees to the right. After plunging from 37,000 feet to 15,000, it vanished from Greek radar screens.

According to Greece’s civil aviation chief, calls from Greek air traffic controllers to flight MS804 went unanswered just before it left Greek airspace, and it disappeared from radar screens soon afterwards.

There was no official indication of a possible cause, whether technical failure or sabotage by ultra-hardline Islamists who have targeted airports, airliners and tourist sites in Europe, Egypt, Tunisia and other Middle Eastern countries over the past few years.

The aircraft was carrying 56 passengers – with one child and two infants among them – and 10 crew, EgyptAir said. They included 30 Egyptian and 15 French nationals, along with citizens of 10 other countries.

Asked if he could rule terrorist involvement, Prime Minister Ismail told reporters: “We cannot exclude anything at this time or confirm anything. All the search operations must be concluded so we can know the cause.”

French President Francois Hollande also said the cause was unknown. “No hypothesis can be ruled out, nor can any be favoured over another.”

With its archaeological sites and Red Sea resorts, Egypt is a traditional destination for Western tourists. But the industry has been badly hit by the downing of a Russian Metrojet flight last October, in which all 224 people on board were killed, as well as by an Islamist insurgency and a string of bomb attacks.