YANGON (Reuters) -- Myanmar reopened its National Convention for the last time on Wednesday to finish drafting a new constitution dismissed by critics as a ploy by the military junta to entrench its rule.

The convention, the first step on the former Burma’s seven-stage “road map to democracy”, would wrap up in about two months, Information Minister Kyaw Hsan told reporters at a tightly guarded camp 40 km (25 miles) north of Yangon. But the junta, which picked most of the 1,058 delegates to the fifth session of the convention since 2004, refuses to set a timetable for completing its “road map”. Kyaw Hsan said a referendum on the new charter would be held “not very long” after the constitution was completed. Western governments and other critics say it is nothing but a smokescreen to preserve the generals’ grip on power, especially while opposition figures such as Nobel laureate Aung San Suu Kyi remain under house arrest. In May, the military extended its detention of Suu Kyi, leader of the National League for Democracy (NLD), which is boycotting the convention, for another year. She has spent nearly 12 of the past 17 years under some form of detention. Critics point to a key objective of the convention, which ensures a “leadership role” for the army in politics. It would reserve key cabinet positions and 25 percent of the seats in a future parliament for serving military officers. “The generals who run Burma have trumpeted the convention as a vehicle for a return to civilian rule and the rule of law,” said Brad Adams, Asia director of Human Rights Watch. “But they have engineered the outcome to ensure the military remains in control and excluded the people of Burma from the process,” he said in a statement. The military, which has ruled Myanmar since 1962, started the on-again-off-again convention process in early 1993 but never committed to a timetable to complete the exercise it says will create a “disciplined democratic system”