Aung San Suu Kyi made a fresh call Tuesday for changes to Myanmar's junta-era constitution as lawmakers began a debate that will test the army's determination to preserve its political power before landmark elections.

The opposition leader has campaigned relentlessly for changes to a charter that bars her from the presidency, focusing on clause 436 that effectively hands the army a veto over any amendments.

"If we want genuine change in this country we must amend 436," she said in a statement to AFP.

The clause calls for a 75 percent majority in votes on major constitutional changes, ensuring that unelected soldiers -- who are reserved a quarter of the parliamentary seats -- have the final say.

Debate on the issue, as well as the provision barring Suu Kyi from the presidency, began on Tuesday and is scheduled to run until Thursday when a vote is expected.

The discussions could be the last opportunity for a vote on major charter change before elections later this year.

Those polls, slated for October or November, are seen as a test of the country's emergence from almost half a century of brutal military rule.

The army has so far vociferously rejected any change in its voting privileges.

Suu Kyi, who was locked up for some 15 years by the former junta, entered parliament in 2012 as reforms under a quasi-civilian government blew through the long-cloistered nation.

Her National League for Democracy Party is widely expected to win many seats in the election.

It garnered some five million signatures in a nationwide petition on charter change last year.

Under the current constitution the Nobel laureate, who has warned that reforms are stalling, is barred from becoming president under a clause that excludes those with foreign spouses and children from top political office. Her sons are British as was her late husband.

Draft proposals put to parliament earlier this month slightly reduced the voting threshold for amendments, from 75 percent to 70 percent, making it easier for elected lawmakers to vote them through.

But it kept the provision that bars Suu Kyi, who turned 70 on Friday, from becoming president.

During Tuesday's parliamentary debate, fellow NLD MPs urged for an end to the army veto.

"The nation could get into a chaotic situation because of constitutional difficulties," Khin San Hlaing, an NLD MP for Pale township, Sagaing, said.

Other MPs from outside the NLD also proposed a lower threshold of around two thirds.

Myanmar's top political post is selected by parliament in a vote by MPs after the election.

The NLD last competed in a nationwide vote in 1990, when it won by a landslide but was never allowed to take power.