Myanmar has invited ASEAN to send five observers and 18 parliamentarians to witness the vote, at which 48 seats are at stake, the 10-member Association of Southeast Asian Nations said in a statement.
The April 1 polls, which will see Nobel laureate Aung San Suu Kyi stand for a seat in parliament for the first time, are viewed as a key test of the military-backed government's commitment to budding reforms.
Observers believe the regime wants Suu Kyi to win a seat in the polls to give its reformist programme legitimacy and spur the West into easing sanctions against the country.
A 2010 election which swept the army's political allies to power was marred by widespread complaints of cheating and intimidation.
Foreign election observers and international media were not allowed into the country for that vote, which was denounced by Suu Kyi's opposition party and Western powers as lacking legitimacy.
Suu Kyi's opposition party cannot threaten the ruling party's majority even with a strong result in next month's polls, but a Suu Kyi win would lend legitimacy to the fledgling parliament.
Her National League for Democracy (NLD) party won a landslide victory in an election in 1990, but the then ruling junta never allowed the party to take power.