The dispute comes at an awkward time for Thailand, which is due to take over the rotating chairmanship of 10-nation Asean grouping next week.
On Monday Thai and Cambodian meeting in Bangkok failed to resolve mutual claims over land near the temple, saying that troops would remain in the area.
The two sides decided that troops on the border would not be increased and that negotiations would continue at an unspecified time.
Thailand has more than 500 troops deployed in the area while Cambodia has sent about 1,000.
|Thailand and Cambodia say they will both keep troops at the border [AFP]
On Tuesday Cambodia's foreign ministry said it had asked for assistance from the UN Security Council and Singapore, host of the Asean security meeting, to resolve the border issue.
Responding to Cambodia's request, Lee Hsien Loong, Singapore's prime minister, said Asean "could not stand idly by without damaging its credibility.
"The situation has escalated dangerously," he added.
Later on Tuesday foreign ministers from the 10 Asean member states held a special lunch meeting on the sidelines of their annual gathering in Singapore.
"This is unscheduled. That illustrates to us how important it is," Rais Yatim, the Malaysian foreign minister, said.
"It could be a test for Asean for the first time [since] two of Asean members are facing a border predicament."
The 10-member Asean usually avoids interfering in each other's domestic affairs although that appears to be changing in a bid to give the group greater relevance.