A Thai soldier patrols near Preah Vihear temple in July.

At least two Cambodian soldiers were killed and one injured in brief fighting with Thai troops around Preah Vihear temple Wednesday, the Ministry of Foreign Affairs said, warning that further violence could lead to "large scale" hostilities between the two countries.

Fighting took place at Viel Intry, or Eagle Field, a patch of land near Preah Vihear temple, as well as at the Keo Sikha Svara pagoda and Phnom Trap, the ministry said in a statement.

The Keo Sikha Svara pagoda has been at the heart of a months-long military standoff that followed the inscription at Cambodia's request of Preah Vihear temple on a Unesco list of World Heritage sites in July.

On Wednesday afternoon, "Thai troops launched heavy armed attacks on the Cambodian troops…in an apparent attempt to force the Cambodian troops out of their present positions inside Cambodian territory," the Foreign Ministry said.

The Cambodian government protested "repeated and very serious armed provocations by Thailand, which could lead to large scale armed hostilities between the two countries" and reserved the right to defend itself, the ministry said.

"In spite of this armed clash between the soldiers on both sides, Cambodia still considers it a clash between soldiers and not a deliberate intent of Thailand," Foreign Minister Hor Namhong told reporters late Wednesday.

No immediate response was available from the Thai government. Both sides said the other fired first, the Associated Press reported Wednesday.

At least six Thais were injured in the fighting, Lt. Col. Phuk Sary, an officer with military Division 12, said late Wednesday.

A Reuters photographer at Preah Vihear temple reported rocket fire from the Thai side Wednesday afternoon.

The foreign ministers for each country failed to reach an agreement on troop withdrawal or border demarcation Monday, following which Prime Minister Hun Sen announced Thai troops were encroaching on a "life-and-death battle zone" at Eagle Field and gave the Thai military one day to pull back.

Cambodian officials said Tuesday the Thai soldiers had withdrawn from Eagle Field, but Thai officials said they would keep soldiers nearby and were not withdrawing troops.

The Cambodian Foreign Ministry said Wednesday Thailand had "increased troops at the border locations with heavy weapons, including artillery and tanks."

Preah Vihear temple's July 7 inscription as a World Heritage site stirred nationalism on both sides and sparked massive protests in Bangkok.

Relations between the two countries are generally civil, but nationalism can boil over. In 2003, Cambodian rioters sacked the Thai Embassy in Phnom Penh and spent a night looting and burning Thai businesses, following untrue media reports that a Thai actress had claimed the famed temples of Angkor Wat should belong to Thailand.

On Wednesday night Cambodian police stood guard over the new Thai Embassy.