Prime Minister Abhisit Vejjajiva and his Cambodian counterpart Hun Sen are expected to meet and discuss the Preah Vihear dispute during the Asean-Europe leaders summit in Brussels in October, Asean secretary-general Surin Pitsuwan says.
Mr Surin spent two hours discussing the border dispute at the private residence of Prime Minister Hun Sen in Phnom Penh on Monday.
He was invited earlier in the day to meet Cambodia's Foreign Minister Hor Namhong and together they also discussed the border dispute.
Press reports said Mr Surin was in "listening" mode during his meetings with Hor Namhong and Hun Sen.
His discussions with top Cambodian leaders was a coincidence as he was visiting Phnom Penh to attend two functions.
The first was a Tabletop Exercise on Pandemic Management organised by USAid and the United Nations.
Mr Surin also joined a delegation of Thai Muslims to meet with Cambodian Muslims in Phnom Penh, a meeting organised at the invitation of Hun Sen.
Speaking while in transit in Bangkok to Jakarta, Mr Surin told the Bangkok Post last night: "I expect the two leaders to meet and discuss the issue during the Asia-Europe Meeting in Brussels".
The Asem summit, to be attended by leaders from 47 countries from Europe, Asean and other countries in Asia, would be held on Oct 4 and 5.
Mr Surin did not elaborate on the details of his discussion with Hun Sen and nor did he say if there were any pre-conditions for the meeting between Mr Abhisit and Hun Sen.
Cambodia has insisted that Asean and the UN mediate the border dispute. Hor Namhong has sent a letter to his Vietnamese counterpart, who is the present Asean chair, urging Asean to mediate. Hun Sen has appealed to the UN.
Prime Minister Abhisit does not want Asean or the UN to become involved.
Mr Surin would only say that Asem was "a good opportunity" for both leaders to exchange views on the dispute.
Thailand and Cambodia engaged in a diplomatic spat after Thailand lobbied the World Heritage Committee (WHC) meeting in Brazil last month to postpone the approval of the management plan on Preah Vihear temple for another year.
Thailand says the plan includes the area disputed by the two countries.
Bangkok insists the overlapping area near the temple should be demarcated before the committee makes a decision on the plan.
The temple has been included on the world heritage list since 2008. The WHC requires Cambodia to submit a plan to manage the area.