The South Asia Free Trade Agreement, or SAFTA, came into effect Sunday, paving the way for free trade of goods among the member nations.
India's Commerce Minister Kamal Nath said implementation of the accord will benefit the entire region - a home to 1.5 billion people.
Under the agreement, the more developed member countries - India, Pakistan and Sri Lanka - will reduce their customs duties to between zero and five percent by the year 2013.
Less developed Bangladesh, Bhutan, the Maldives and Nepal have until 2018 to do the same.
Leaders of the South Asian Association for Regional Cooperation, or SAARC, agreed to forge ahead with the free trade zone at their summit in Pakistan in 2004.
Some information for this report provided by AP.
