Thai and Cambodian troops have broken a brief ceasefire in new clashes which left one Thai solider dead.
The fighting shattered hopes of a quick end to a long-running border conflict. The death toll rose to 16.
The fighting eased shortly after dawn as nearly 100,000 displaced residents on both sides waited to see if the worst skirmishes in years between the two South-east Asian neighbours might finally end.
Thailand and Cambodia have clashed six times since 2008 over the border.
The land has been disputed for more than half a century, but analysts say domestic politics on both sides is driving the conflict.
Field commanders agreed to the brief truce on Thursday but Cambodian Col Suos Sothea said the Thai army fired artillery shells into Cambodia again early Friday.
Thai army spokesman Col Sansern Kaewkamnerd blamed Cambodia for breaking the deal.
The director of Phanom Dongrak hospital confirmed one Thai soldier was killed, bringing the total dead to 15 soldiers and one civilian.