Airlines were assessing their options for Middle East flights on Monday after conflict that had already disrupted major routes entered a new phase.

The situation followed the United States striking key Iranian nuclear facilities, and Teheran pledging to defend itself.

International airlines have canceled flights to aviation hubs in recent days, such as Dubai, the world's busiest international airport, and Doha in Qatar. The cancelations highlight the escalating concerns within the aviation industry regarding the region.

The usually busy airspace stretching from Iran and Iraq to the Mediterranean has been largely empty of commercial air traffic for 10 days, after Israel began strikes on Iran on June 13, with airlines diverting, canceling, and delaying flights throughout the region due to airspace closures and safety concerns.

Finnair was the first to announce a prolonged suspension of flights to Doha, with cancelations announced up until June 30.

Leading Asian carrier Singapore Airlines, which described the situation as "fluid", moved to cancel flights to Dubai through to Tuesday.

Air France, Iberia, British Airways, and Kazakhstan's Air Astana all canceled flights to either Doha or Dubai, both on Sunday and Monday.

Air France also canceled flights to Riyadh and said it would suspend flights to and from Beirut, Lebanon until Wednesday.

A spokesperson for Iberia said the carrier has not made a decision regarding later flights. British Airways said its teams were keeping the situation under review.

Carriers are likely avoiding airports in the United Arab Emirates, Qatar, and, to a lesser extent, Kuwait, Bahrain, and Saudi Arabia, due to concerns that Iran or its proxies will target drone or missile attacks on US military bases in the countries, aviation risk consultancy Osprey Flight Solutions said.

Added to increased fuel and crew costs from long detours and cancellations, carriers also face a potential hike in jet fuel costs because of oil price rises that followed the US attacks.

Australia-based Flight Centre Travel Group said it is getting a small number of customer requests to route journeys to Europe away from Middle Eastern hubs.

"The most common transfer hubs that we're seeing requested are Singapore, Hong Kong, Johannesburg, or even direct between Perth and London," said Graham Turner, CEO of Australia-based Flight Centre Travel Group.

Meanwhile, Flightradar24 told Reuters it had seen a "dramatic increase" in jamming and spoofing in recent days over the Gulf region. SkAI, a Swiss company that runs a GPS disruption map, said on Sunday it had observed more than 150 aircraft spoofed in 24 hours there.