The Maldives government has released a prominent "cyberdissident" Fathimath Nisreen, the pressure group Reporters Without Borders (RSF) says.
Two of the four sentenced in 2002 remain in detention
"It's a huge delight," an RSF spokesman said. "This courageous young woman can finally resume a normal life."
RSF said Ms Nisreen had spent three years in prison, and then house arrest.
The Maldives authorities in London have not commented on the release, but said at the time of her conviction she was involved in "criminal" activities.
'Abuses and corruption'
In a statement released on Monday, RSF said it hoped the amnesty awarded to Fathimath Nisreen would quickly be followed by the release of Mohamed Zaki and Ahmad Didi.
They and another man, Ibrahim Lutfy, were all arrested in January 2002 for working for Sandhaanu, an e-mail newsletter that exposed "human rights abuses and corruption" in the Maldives.
Mr Zaki, Mr Didi and Mr Lutfy were all sentenced to life imprisonment in July 2002. Mr Lutfy escaped from police custody 18 months into his sentence while receiving eye treatment in Sri Lanka.
The trio were accused of "defamation" and "attempting to overthrow the government". Ms Nisreen, who was only 22 at the time of the trial, was jailed for 10 years, later reduced to five years detention on an island south of the Maldivian capital, Male.
"Despite everything let us not forget that the iniquitous justice system in this country has deprived Fathimath of three years of her life," RSF said.
"At less than 25, she has already been sent twice to prison and been banished for long months on an island far from her family.
"We hope that the amnesty that has just been granted is the first sign of a commitment by Maldives President Maumoon Abdul Gayoom to respect free expression in future."
RSF says Fathimath Nisreen had to sign a paper officially accepting the amnesty but in which she undertook to "respect the Islamic religion" and "the Maldives constitution".
"It is certain that international pressure played a big part in my release," she is reported to have said.
RSF says that since the summer of 2004 she had been allowed to return to the capital, Male, where she lived under house arrest.
Mr Didi and Mr Zaki have also been under house arrest since February 2004. RSF says that their sentences were reduced to 15 years in 2003.
Mohamed Zaki - life in prison, sentence later reduced to 15 years, now under house arrest
Ibrahim Lutfy - life in prison, but escaped 18 months into his sentence
Ahmed Didi - life in prison, sentence later reduced to 15 years, now under house arrest
Fathimath Nisreen - 10 years in prison, now released
A statement sent by the Maldives High Commission in London to the BBC in 2003 said that the charges against the four were "purely criminal and not motivated by any other reason except to enforce the penal laws" of the Maldives.
It said that the electronic newsletter for which they worked "was not a newsletter registered anywhere with any authority".
Its authors were anonymous, "proving the nature of the activities they were engaged in".
The statement said they had been found guilty of inciting people "to violence and violent and illegal acts against a lawfully elected government and its officials".