Suu Kyi's National League for Democracy (NLD) dominated 2015 elections ending decades of military-backed rule.

But because of a 2008 charter scripted by the military, the NLD was forced into an uneasy power-sharing agreement.

The constitution grants the armed services control of security ministries and a quarter of unelected parliamentary seats.

That hands the military an effective veto over constitutional change.

But the NLD-dominated parliament voted earlier this month to form a cross-party committee to look at reforms of the charter, a key campaign pledge.

The party will be allocated 18 out of 45 seats on the panel, the military will have eight and the remainder will be divided between other parties.

There has been no detail about the specific reforms, but military MPs stood up in protest when the idea was first mooted.

Major General Tun Tun Nyi told reporters in Yangon that 45 people is not enough to review the charter and the process "would not be fair".

Tun Tun Nyi said the army is not opposed to amendments but "we are rejecting trying to change the constitution this way".

Brigadier General and military MP Than Soe said they would take part in the panel but would oppose changes to the "essence of the constitution", echoing rare comments by commander-in-chief Min Aung Hlaing in an interview this month with Japanese paper Asahi Shimbun.

Debates over the constitution are highly sensitive in Buddhist-majority Myanmar, especially among nationalist movements.

The military is still fighting with ethnic armed groups in border areas and has said its role in politics is necessary for stability. But critics say it does not want to relinquish influence.

The 2008 charter also prevents anyone with a foreign spouse from becoming president, a measure believed to be aimed at Suu Kyi, who had a family with the late British academic Michael Aris.

The decision to form the panel came just a few days after a court handed death sentences to the killers behind the 2017 murder of Muslim lawyer and Suu Kyi advisor Ko Ni.

He was leading the charge on constitutional reform when he was shot dead in cold blood at Yangon airport, while cradling his grandson.

Ko Ni also helped craft the position of state counsellor for Suu Kyi after the election since she could not be president.

Tun Tun Nyi reiterated opposition to that legal manoeuvre, calling it "beyond the constitution", which is why "we condemned it when it was discussed."