A diplomatic row has broken out between Thailand and Cambodia over former Thai Prime Minister Thaksin Shinawatra's new job as an adviser to the government in Phnom Penh.
This dispute is only the latest of a series of spats between the two countries. The BBC looks at the main issues dividing them.
THAKSIN'S NEW ROLE
Cambodia has angered the Thai government by refusing to extradite Thaksin Shinawatra, who is in Cambodia after accepting a role as an economic adviser to the government there.
Cambodia said it rejected the extradition request because it viewed the charges against Mr Thaksin as being politically motivated.
Mr Thaksin was Thailand's prime minister for more than five years, but was ousted in a military coup in September 2006, accused of corruption and abuse of power.
He has been sentenced to two years in jail in absentia by a Thai court over a conflict of interest case.
Mr Thaksin is a close friend of Cambodian Prime Minister Hun Sen
Thailand has withdrawn its ambassador from Phnom Penh in protest at Cambodia's protection of Mr Thaksin.
The timing of the spat is particularly embarrassing for Thailand, as it comes just before Thai Prime Minister Abhisit Vejjajiva is to chair a meeting between regional leaders and US President Barack Obama, on the sidelines of the Asia-Pacific Economic Cooperation (Apec) summit in Singapore.
Some analysts say the Cambodian government of Prime Minister Hun Sen - a close friend of Mr Thaksin and his golf partner - would prefer to have Mr Thaksin back in power in Thailand and is trying to undermine the current Thai administration.
PREAH VIHEAR TEMPLE
The Preah Vihear temple has been at the centre of a border dispute between Thailand and Cambodia for more than a century.
The temple was built mainly in the 11th and 12th centuries, when the Khmer empire was at its height. Its construction was ordered by the kings who commissioned Cambodia's most famous temple at Angkor.
Maps drawn by Cambodia's French colonial rulers and Thailand (or Siam as it was then known) showed the temple as belonging to Cambodia, but in later decades Thailand said the maps were not official and were therefore invalid.
In 1962 the International Court of Justice granted the temple to Cambodia, but Thailand claimed much of the surrounding land, leaving Cambodia's only access to the temple up a steep hillside.
But the territorial row with Thailand lingered on, and in 2001 Thai troops blocked access for more than a year in a dispute about polluted water at the site.
Tensions increased in July 2008, after Cambodia's successful bid to have the temple listed as a World Heritage site.
In April this year, troops from both sides exchanged fire across the disputed border. Thai authorities said at least two Thai soldiers died and seven were wounded.
MARITIME OIL AND GAS
After Cambodia appointed Mr Thaksin as an economic adviser last week, the Thai cabinet decided to cancel a memorandum of understanding on joint oil and gas exploration in the Gulf of Thailand.
Both countries claim overlapping areas in the gulf, which are believed to be rich in gas and oil.
Thailand issued petroleum concessions in the area in the 1970s, although no work was carried out because of the disputed claims. Cambodia in turn awarded exploration deals in 1997 subject to the settling of the dispute.
Cambodia claims Thailand cannot now unilaterally revoke the memorandum of understanding, saying it is against international law.
Simmering resentment between Cambodia and Thailand goes back centuries - to well before the modern countries existed - when rival Siamese and Khmer kingdoms fought each other for territory and power.
European colonial expansion forced a sometimes arbitrary definition of borders, which in some areas continue to be disputed.
While bilateral trade has flourished with massive Thai investment in Cambodia, the relationship has remained uneasy.
Cambodian disenchantment with Thailand flared into violence in 2003 when a Thai actress - popular both at home and in Cambodia - allegedly said that the 900-year-old temple complex at Angkor belonged to Thailand and should be returned.
Suvanant Kongying denied making the remarks, but the Thai embassy in Phnom Penh was badly damaged by rioters.
One person was killed and several injured in the riots and many Thai businesses were also destroyed.
Cambodians see Angkor Wat as a vital part of their identity but over the centuries there have been times when the temple complex has been occupied by Thai forces.