Cambodian soldiers attacked a Thai outpost at Phu Ma Khua in the disputed border area several times overnight, but were repulsed, the Bangkok Post reported.
Thai army spokesman Sansern Kaewkamnerd said the Cambodian troops threw hand grenades at the Thai position and tried to break through the fence around the post, but were repelled by Thai soldiers throwing hand grenades.
Cambodian forces renewed the attack hours later, this time directing machine gun fire, mortar rounds and rocket-propelled grenades at the Thai position. The Thai troops returned fire and pinned down the attackers, the spokesman said. Sporadic exchanges of fire continued until 5 am on Wednesday.
Cambodia and Thailand accused each other of violating the permanent ceasefire proposed by the United Nations Security Council on Monday.
The Thai army spokesman said the attacks showed Cambodian forces were paying no attention to the United Nations Security Council's call for a permanent ceasefire.
The Cambodian Ministry of Foreign Affairs said in a statement that Thai forces fired grenades and 81mm mortars into the Phnom Trop area close to Preah Vihear between 9:00pm on Tuesday and 5:00am yesterday.
"This violation of the ceasefire by Thai armed forces clearly shows that the real intention behind Thailand's insistence on resolving the matter bilaterally is to use its overwhelming superior military forces to take over Cambodian territory in the vicinity of the temple of Preah Vihear," read the statement, as cited by the Phnom Penh Post.
It added that Cambodian troops did not respond to the Thai "provocation."
Tensions first escalated between the two countries in July 2008 following the build-up of military forces near the Preah Vihear temple, which dates back to the 11th century and is located on the Cambodian side of the border. The Hindu temple was inscribed on the World Heritage List of the UN Educational, Scientific and Cultural Organization (UNESCO) that same month.
Clashes between the two countries resumed earlier this month, prompting calls for calm and restraint by UN Secretary-General Ban Ki-moon as well as UNESCO Director-General Irina Bokova.