Several members of Aung San Suu Kyi's opposition party have been detained by Myanmar authorities after protests against crippling power cuts, officials from her National League for Democracy (NLD) said Tuesday.

Around 1,500 people joined a rally in the country's second-largest city of Mandalay late Monday against severe electricity shortages, in the biggest protest since a Buddhist monk-led uprising was crushed five years ago.

"As far as I know, three (NLD) people were taken for questioning by the authorities," Ohn Kying, an NLD member of parliament from Mandalay, told AFP. "We don't know why they were taken."

A second NLD MP said five people were held after the protest against shortages, which have left the city with as little as four hours of power a day.

"The authorities didn't give any reason... I assume it is connected to the protest," said Zaw Myint Maung, an NLD MP from Kyaukpadaung township in Mandalay.

Protests are rare in the country formerly known as Burma, where pro-democracy rallies in 1988 and 2007 were brutally crushed by the junta.

Under a new law, one of a slew of reformist moves by President Thein Sein's government since the end of army-rule last year, authorised protests have been permitted, but the demonstrators in Mandalay did not have permission when they began their rally.