The sound heard in the last cockpit recording of a Russian passenger plane which recently crashed in Egypt was caused by a bomb explosion, an investigator says.

The indications and analysis so far of the sound on the black box indicate it was a bomb, a member of the Egyptian team investigating the crash said on Sunday. 

We are 90 percent sure it was a bomb, Reuters quoted the unnamed source as saying.

The source did not reveal further details.

Egyptian officials say they are investigating all possibilities having caused the deadly incident.

The Airbus A321, which was on its way to Saint Petersburg crashed in the Sinai Peninsula on October 31, minutes after it took off from the Egyptian Red Sea resort of Sharm al-Sheikh, leaving all 224 people on board dead.

On Saturday, the head of the investigating committee, Ayman al-Muqaddam, announced that a sound was heard in the final second of the recording.

He said that parts of the plane were scattered over an area of 13 kilometers (8 miles), “which is consistent with an in-flight break up.”

Egyptian army soldiers stand guard next to the luggage and belongings of passengers of the A321 Russian airliner piled up at the site of the crash in Wadi el-Zolmat, a mountainous area in Egypt's Sinai Peninsula on November 1, 2015. (AFP photo)

Meanwhile, thousands of Russian and British tourists remain stranded in Egypt.

Moscow suspended all flights to Egypt, while the UK has halted flights to Sharm al-Sheikh. A number of other countries have also warned their nationals against flying to the resort over security concerns.

A report released on Saturday by the Daily Mail newspaper that a Thomson Airways British tourist plane heading in to land at the Egyptian resort of Sharm el-Sheikh on August 23, came within 1,000 feet (300 meters) of a missile.

Militants from Velayat Sinai (Sinai Province), previously known as Ansar Bait al-Maqdis, had earlier circulated a statement on social media claiming responsibility for the plane crash. They said the group brought down the aircraft in revenge for Russian airstrikes against Daesh positions in Syria. Velayat Sinai pledged allegiance to Daesh in November 2014.