Mohamed Nasheed asked India to help release prisoners and the US to curb leaders' financial transactions.
Turmoil began when current President Abdulla Yameen refused to release political dissidents, defying a court order and sparking protests.
"We must remove him from power," Mr Nasheed said in a statement.
The government has declared a state of emergency and the chief justice of the Supreme Court has been detained with no further details given about his detention or charges.
The opposition has called his arrest and that of another judge a "purge".
There has also been an international condemnation of the government's moves, with the US State Department expressing concern.
Meanwhile, President Yameen gave a televised address to the country, saying judges had been plotting a coup.
Maldives is a nation in the Indian Ocean, made up of 26 coral atolls and 1,192 individual islands, and tourism is a vital part of its economy.
Countries including India, the US, the UK and China have warned tourists to be cautious, especially near political rallies, although the UK government has advised that areas away from the capital, including the international airport, remained safe.
What did the ex-President ask for?
Mr Nasheed called on the Indian government to send an envoy, backed by its army, to release political detainees whose detention is at the heart of a worsening political crisis.
"We request a physical presence," he said, after stating that he was speaking "on behalf of Maldivian people".
He also asked the US to restrict Maldivian leaders' transactions through US banks.
In a statement, Mr Nasheed added: "President Yameen has illegally declared martial law and overrun the state. We must remove him from power."
Mr Nasheed was an opposition leader under a former government and became the country's first democratically elected leader in 2008, but was ousted and jailed in 2012. He is currently thought to be in neighbouring Sri Lanka.
A Maldives minister to the UN, Jeffrey Salim Waheed, called his intervention "treason" and "the single biggest attempt to undermine the Maldives sovereignty"
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