Russian plane crash
A flower is seen near debris at the crash site of a Russian airliner in al-Hasanah area in El Arish, Egypt, Nov. 1, 2015. Reuters/Mohamed Abd El Ghany

UPDATE: 2:35 p.m. EST: The Irish Aviation Authority has directed airlines to avoid the Sinai Peninsula, just hours after Downing Street said flights would be canceled and delayed to and from the Sharm el-Sheikh Airport. The announcement comes as authorities continue to investigate whether terrorism could have been behind Saturday’s deadly Russian airplane crash over Egypt.

Original Story:

The British government has expressed concern that the Russian airplane that crashed in Egypt over the weekend may have been brought down in an attack. In response, all flights scheduled to depart the United Kingdom for Sharm el-Sheikh, Egypt, will be canceled Wednesday evening to allow time for an investigation of the cause of the plane crash.

“While the investigation is still ongoing, we cannot say categorically why the Russian jet crashed,” Downing Street said, according to Sky News. "But as more information has come to light, we have become concerned that the plane may well have been brought down by an explosive device."

Airbus A321M crashed Saturday in the Sinai shortly after its departure for Russia. None of the 224 passengers on board the flight survived. Various theories have been considered for what may have happened to the airliner, but officials have said it will take time to know for certain. Investigators managed to extract content from at least one of the two black boxes that were recovered from the crash site Wednesday.

Downing Street said all flights leaving Sharm el-Sheikh for the U.K. were subject to delays. "That will allow time for a team of U.K. aviation experts, currently traveling to Sharm, to make an assessment of the security arrangements in place at the airport and to identify whether any further action is required," officials said in a statement.

The Sinai Province, an Egyptian militant group that has pledged allegiance to the Islamic State group, also known as ISIS, has taken responsibility for causing the plane to crash. A video surfaced Wednesday that appeared to show ISIS fighters brandishing bowls of sweets and smiles in celebration of the alleged attack.

Russian, Egyptian and U.S. officials have cast doubt on the militants’ claim of responsibility, with the Egyptian president calling it “propaganda.” Officials said they did not believe ISIS had technology capable of bringing down an airline, and some have speculated that there may have been technical difficulties or an explosion on board.

Russia intervened in Syria in late September and has worked to bolster Syrian President Bashar Assad. While much of the campaign has focused on anti-Assad rebels, including those backed by Western governments, the Russia campaign has recently stepped up its attacks on ISIS. Fighters with the militant group have warned Russia of attacks in recent months.