The Foreign Ministry on Thursday issued a travel warning urging Israelis to stay away from the border between Thailand and Cambodia in light of an escalating military conflict between the two Southeast Asian countries.

“Due to the growing tensions between Thailand and Cambodia, the Foreign Ministry recommends that Israeli travelers avoid entering or staying in the border area between the two countries, particularly in the northeastern provinces of Thailand and the northwestern provinces of Cambodia,” the ministry said in a statement.

On Thursday, weeks of tension over a Thai-Cambodian border dispute escalated into clashes that have killed at least 12 people in Thailand, including 11 civilians. Thailand and its neighbors are among the most popular flight destinations for Israeli tourists, with some statistics showing an average of around 200,000 Israelis per year visiting Thailand.

The Foreign Ministry warning focused on the border area, advising travelers to avoid “proximity to border crossings, most of which are currently closed.”

The warning added, “We recommend following reports in the local media and adhering to the instructions of security authorities as they are issued.”

The armed clashes that broke out Thursday occurred in long-disputed border areas, rapidly escalating months-long tensions. The fighting included gunfire exchanges and shelling as well as rocket fire, which Thai authorities said killed a number of civilians in three provinces. Thailand responded with airstrikes.

It was the second armed confrontation since a Cambodian soldier was shot dead in May and a major escalation that came hours after the two countries downgraded diplomatic relations following a land mine explosion that injured Thai soldiers.

Both countries accused each other of starting the clash early on Thursday.

“We have used air power against military targets as planned,” Thai army deputy spokesperson Richa Suksuwanon told reporters. Thailand also closed its border with Cambodia.

Cambodia’s defense ministry said the jets dropped two bombs on a road, and that it “strongly condemns the reckless and brutal military aggression of the Kingdom of Thailand against the sovereignty and territorial integrity of Cambodia.”

Thai caretaker Prime Minister Phumtham Wechayachai told a press conference that there had been no declaration of war and conflict was not spreading into more provinces, but that fighting must stop before negotiations start.

He said Cambodia had fired heavy weapons into Thailand without any specific targets, resulting in civilian deaths.

Border disputes have long caused periodic tensions between the two neighbors. Thailand and Cambodia share more than 800 kilometers (500 miles) of land border.

The contesting claims stem largely from a 1907 map drawn under French colonial rule that was used to separate Cambodia from Thailand. Cambodia has been using the map as a reference to claim territory, while Thailand has argued the map is inaccurate.

The most prominent and violent conflicts have been around the 1,000-year-old Preah Vihear temple.