Why have tensions escalated between Thailand and Cambodia - and is it safe to travel there?

Military clashes have erupted between Thailand and Cambodia, killing at least 12 people, including 11 civilians.

A long-standing dispute over border areas escalated into an exchange of gunfire, shelling and rockets being launched on 24 July, with both sides accusing one another of initiating the violence. Relations between the Southeast Asian neighbours deteriorated sharply after an armed confrontation in May that killed a Cambodian soldier.

Nationalist passions on both sides have further inflamed the situation. Here is all you need to know about the situation and how it got to this stage.

What is happening in Thailand and Cambodia? Tensions first broke out on Thursday morning in an area near the ancient Ta Muen Thom temple along the border of Thailand's Surin province and Cambodia's Oddar Meanchey province. The Thai army said that most casualties occurred in the Si Sa Ket province, where six people were killed after shots were fired at a fuel station.

At least 14 people were injured in three other border provinces. An eight-year-old boy was among those killed, Thailand's health minister Somsak Thepsuthin said.

Thailand's foreign ministry said Cambodian troops fired "heavy artillery" on a Thai military base on Thursday morning and also targeted civilian areas, including a hospital. In response, the Thai army said a Thai F-16 fighter jet bombed military targets in Cambodia.

Cambodia's defence ministry said Thai jets had dropped bombs on a road near the ancient Preah Vihear temple, saying it "strongly condemns the reckless and brutal military aggression of the Kingdom of Thailand against the sovereignty and territorial integrity of Cambodia". Clashes are now thought to be ongoing in at least six areas along the border, the Thai defence ministry said.

What caused the escalation? For more than a century, Thailand and Cambodia have laid claim to undisputed points along their 817-km (508-mile) land border. This has led to skirmishes over several years and at least a dozen deaths, including during a weeklong exchange of artillery in 2011.

Tensions were reignited in May after a Cambodian soldier was killed during a brief exchange of gunfire, which escalated into a full-blown diplomatic crisis and now has triggered recent armed clashes. Both countries agreed to de-escalate tensions, but Cambodian and Thai authorities continued to implement or threaten restrictions on the other.

Tighter restrictions on Thailand's land border with Cambodia were implemented, stopping almost all crossings except for students, medical patients and others with essential needs. Thai authorities sealed the border entirely after Thursday's escalation.

Meanwhile, Cambodia has banned Thai movies and TV shows, stopped the import of Thai fuel, fruits and vegetables and boycotted some of its neighbour's international internet links and power supply. Earlier on Thursday, Cambodia said it was downgrading diplomatic relations with Thailand to their lowest level, expelling the Thai ambassador and recalling all Cambodian staff from its embassy in Bangkok.

That was in response to Thailand withdrawing its ambassador and expelling the Cambodian ambassador a day earlier, in protest against a number of land mine blasts that injured a total of eight Thai soldiers. Thai authorities alleged the mines were recently laid along paths that by mutual agreement were supposed to be safe.

They said the mines were Russian-made and not of a type used by Thailand's military. Cambodia accused Thailand of making "baseless accusations.