Russia and Egypt have dismissed claims from U.S. and U.K. officials that a bomb was the likely cause of the Metrojet plane crash in the Sinai Peninsula on Saturday, calling the reports "speculation."

According to The Washington Post, Egypt's civil aviation ministry said the claims were "not based on facts" and that the country's airports were secure by international standards.

"The investigation team does not have any evidence or data confirming this hypothesis," the ministry said in a statement.

On Wednesday, British Foreign Secretary Philip Hammond announced on television that there was "a significant possibility that the crash was caused by an explosive device on board the aircraft."

British Prime Minister David Cameron also backed the claims.

The British government suspended flights to the Egyptian resort city Sharm el-Sheikh on Wednesday. Plans are in motion to evacuate 20,000 Britons currently on vacation at the resort.

Ahmed Abou Zeid, spokesman for Egypt's Foreign Ministry, criticized the decision, saying it was made without any input from the Egyptian government.

Prime Minister Cameron invited Egyptian President Abdel Fatah al-Sissi to meet in the U.K. to discuss the issue.

Russian presidential spokesperson Dmitri Peskov said Britain's bomb theory was based on "unverified information" and that further investigation was warranted.

The Associated Press reports that Germany's Lufthansa Group airline has also suspended flights to Sharm el-Sheikh "due to the current situation on the Sinai Peninsula."

Lufthansa plans to return about 50 German citizens currently in the resort area. The company has also altered flight paths to avoid flying over the Sinai region.

Metrojet Flight 9268 was headed from Sharm el-Sheikh to St. Petersburg on Saturday, when the plane inexplicably dropped from radar 23 minutes after takeoff. The Airbus A321-200 later broke apart in midair, landing in the Sinai Peninsula and killing all 224 people onboard.