"Her house arrest has already been extended," one official was quoted by the AFP news agency as saying.
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Suu Kyi has been confined for 12 of the past 18 years.
Her last spell in detention started on May 30, 2003 "for her own protection" after clashes between her followers and government supporters in the northern town of Depayin.
"We expected they would extend it, although there is no law that would have done that," Sein Win, chairman of the Burmese government in exile, told Al Jazeera.
"We are asking them not only to release her but to talk with her."
On Tuesday, police detained more than a dozen members of Suu Kyi's National League for Democracy (NLD) party after they marched from the party's headquarters to her home.
Suu Kyi's party has rejected the outcome of Myanmar's recent referendum on a military-backed constitution, calling the approval of the text a "sham".
The military government said on Monday that voters in the cyclone-hit country overwhelmingly approved the constitution that critics say will perpetuate the military's decades-old grip on power.
Myanmar exiles angryover cyclone inaction"The referendum is not free and fair," the party said in its first official reaction to the junta's claim of victory.
Myanmar exiles angryover cyclone inaction
The generals said the constitution was approved by 92.5 per cent of voters.
The proposed constitution guarantees 25 per cent of parliamentary seats to the military and allows the president to hand over all power to the military in a state of emergency.
Critics say these provisions go against the military government's professed commitment to democracy.
The new charter would also bar Suu Kyi from running for president.
The Mistral arrived in Thailand on Tuesday, where it planned to unload its cargo for storage in a warehouse.
France said on Sunday that it had given up trying to deliver the shipload of aid, saying it was "shocked" by the resistance of Myanmar's military rulers.
The extension of Suu Kyi's detention is likely to dismay Western donor nations which have pledged tens of millions of dollars in conditional aid since Cyclone Nargis hit on May 2.