Asean ministers also signed an energy agreement to allow members to buy oil at a discounted price during times of crisis, and a declaration on setting up an EU-style Asean community by 2015.
Human rights body
An Asean free trade deal with Australia and New Zealand, which could eventually add $48bn to economies in the region, was signed on Friday.
Economic growth is slowing rapidly in the region, which is largely dependent on exports, and many jobs are at risk.
Singapore is already in recession and analysts say Thailand and Malaysia might be next.
Meanwhile, the leaders broadly agreed on the terms of reference for a much-debated human rights body which will be made operational by the end of this year, but is unclear if it will have the power to punish violators.
Activists were angered on Saturday when the prime ministers of Cambodia and Myanmar refused pro-democracy activists from their countries to attend the summit.
Abhisit Vejjajiva, Thailand's prime minister and currently head of the Asean, said the bloc would "try to ensure that there is civil society participation" in its future work.
Abhisit said on Sunday that leaders held an "open discussion" with Myanmar's prime minister, encouraging the country to co-operate with the United Nations on reform and release of political detainees.