Greece's Foreign Ministry has advised citizens to avoid travel to Saudi Arabia unless absolutely necessary, citing the deteriorating security situation in the Middle East and restrictions on Saudi airspace.
The warning follows a week of Houthi attacks on King Khalid International Airport in Riyadh.
A strike on Saturday killed at least 12 people and wounded about 300, Saudi authorities said, the third attack on the airport in a week.
On Sunday the Saudi-led coalition said an "unidentified projectile" hit Terminal 4 and started a fire, hours after the Iran-backed Houthis told airlines and travelers to stay away from Saudi airports.
The United Nations envoy for Yemen called the attacks a "grave escalation." President Donald Trump has said the U.S. is weighing whether to join Saudi Arabia's offensive against the Houthis.
The ministry told Greeks already in the kingdom to stay in contact with their airline, follow official sources and obey local authorities.
The escalation also touches Greece's military. Athens keeps a Patriot air-defense battery in Saudi Arabia, which Defense Minister Nikos Dendias has said intercepted Iranian missiles aimed at Saudi oil facilities earlier this year. Greece's national security council extended the deployment last week by a month while talks with Riyadh continue.
Opposition parties have criticized the deployment as a risk of entanglement in regional war.
The Greek government has not said whether the latest attacks affect the battery or its crew.