AI said the Association of Southeast Asian Nations (Asean), of which Myanmar is a member; China, Myanmar's closest ally; and Japan were the "best placed to bring the necessary pressure to bear on the Myanmar government".
"The government of Myanmar must free Daw Aung San Suu Kyi at once, without condition, and not return her to house arrest," Benjamin Zawacki, a Myanmar expert for AI, said.
He said that "in the absence of a unified international voice, the Myanmar government will continue to act in utter disregard for human rights.
"Now more than ever, the [UN] Security Council and Asean member states must send an unequivocal signal to the generals that they can no longer act with impunity."
Hillary Clinton, the US secretary of state, said the US was speaking to Asean member states to press Myanmar's ruling generals to release Aung San Suu Kyi.
The 63-year-old Nobel peace laureate has of late been in ill health.
|Aung San Suu Kyi's jailing has sparked protests in other countries [Reuters]
Clinton said officials were also talking to China and other countries to "see if we can't, on a humanitarian basis, seek relief for Aung San Suu Kyi from this latest effort to intimidate and perhaps even incarcerate her".
Asean has long been reluctant to criticise Myanmar, citing its policy of non-interference in members' internal affairs.
But Abhisit Vejjajjiva, the prime minister of Thailand which holds Asean's rotating chair, told the Reuters news agency that the group was "concerned" about the latest developments.
"We would like to see positive steps being taken according to the road map," he said, referring to the military government's self-declared plan for democratic reforms.
"It's very important the political process is inclusive."
China has so far not commented on the Myanmar situation.
The Asean Inter-Parliamentary Myanmar Caucus, a group of Southeast Asian legislators that has been pushing for democratic reforms in Myanmar, criticised the bloc for failing to act.
Kraisak Choonhavan, the president of the caucus, told Al Jazeera it was a shame that Asean has issued nothing more than a mild rebuke over rights abuses in the country.
"Asean cannot have a rogue … as a member because it poses all sorts of problems for Asean"
Kraisak Choonhavan, Asean Inter-Parliamentary Myanmar Caucus
Speaking after a meeting with members of Aung San Suu Kyi's National League for Democracy party, Kraisak said regional bloc has yet to take Myanmar to task for violations.
"Asean countries are quite concerned and yet they have not taken significant steps to address this human rights problem, particularly this latest issue of removing her from house arrest to Insein prison, including her maids," he said.
Kraisak said the ruling generals were "faulting her and trying to persecute her" instead of putting the guards on trial for allowing an American to sneak into her house.
"Asean cannot have a rogue ... I hate to use the word but it is appropriate for this regime ... as a member because it poses all sorts of problems for Asean."
He suggested the Security Council haul Myanmar's generals before the International Criminal Court, as they had done in the case of Omar al-Bashir, Sudan's president.
"The evidence is so clear and [Myanmar] is right on top there," Kraisak said.