A jailed member of the anti-Kremlin punk band Pussy Riot has said the guilty verdict handed to her and two other group members has strengthened her resolve to fight for the removal of Vladimir Putin.

In response to questions posed by the Guardian and handed to the band via their lawyer, Yekaterina Samutsevich described for the first time to western media the conditions the trio face and their reaction to the verdict.

The 30-year-old said she did not fear the two-year sentence handed down by a Moscow judge earlier this month for their performance of an anti-Putin song in Moscow's Orthodox cathedral.

"Of course we didn't expect a not-guilty verdict," she wrote. "To expect justice from a court that ignores all your objections is of course impossible. So we weren't shocked and, to the dismay of our enemies, didn't faint when we got the verdict."

Samutsevich, with Maria Alyokhina, 24, and Nadezhda Tolokonnikova, 22, was found guilty of hooliganism motivated by religious hatred for their February performance, despite insisting it was a form of political protest. Their lightning-quick trial, marked by procedural violations and absurdities, has highlighted the crackdown on dissent in Russia.

"More than anything, our trial showed the dependence of the justice system, and its direct authority, on Putin's power, which clearly should not be the case in a government that calls itself democratic," Samutsevich said. Pussy Riot and their supporters have accused Putin, and the powerful Russian Orthodox church, of orchestrating the case against them.

"Our verdict shows just how scared Putin's regime is of anyone who can undermine its legitimacy," Samutsevich said.

She decried the government's increasingly conservative policies as well as a parliamentary vote in December 2011 that was marred by widespread allegations of fraud. Coming just over two months after Putin announced his plan to return to the presidency following four years as prime minister, they were the catalyst for mass protests that have rocked the capital since.

Pussy Riot, a radical feminist band, was born of those protests. Now, nearly one year after forming, three of the anonymous collective's members have become among Russia's most famous political prisoners. Two other members of the group have reportedly fled the country fearing further political reprisals.

Samutsevich, Alyokhina and Tolokonnikova have been in a pre-trial detention centre in southern Moscow since their arrest in March, and will remain there while lawyers appeal against their sentence. If the appeal is declined, they will be sent to women's prison colonies to serve their two-year sentences while conducting light labour, minus the time they've already served.

"We are all held in special cells, each made for four people, and we're all in separate cells, on different floors," Samutsevich wrote in a tiny scribble. "There are three other people in my cell, here for economic crimes. They are calm, intelligent people who support me and the ideas of our group.

"This isn't surprising, because now only blind people can't see that since March 2012, Putin's regime has moved to direct repressive actions, starting with a major campaign against all dissenters, under which our group was one of the first to fall."

Government critics have spoken of an increased campaign of intimidation since Putin's re-election in the controversial March vote. Several other activists, including the opposition leader Alexey Navalny, are facing criminal charges.

"We are mentally prepared [for jail]," Samutsevich wrote. "I don't see anything super-scary in having to serve 1.5 years and work. I don't think that it'll become some sort of especially difficult test for us – we've already lived through the past five months relatively easily and the evil plan of our authorities, to jail us so as to break us and sour us, has already failed miserably.

"The problem for Putin personally now is that a lot of people no longer see his strong hand and authority, but his fear and uncertainty in the face of the progressive citizens of Russia, who grow more and more numerous with every step like our verdict," Samutsevich wrote.

The trial has driven a further wedge through Russian society, splitting mainly urban liberals from the more traditional heartland that was largely insulted by the women's performance. Yet opposition to Putin continues to grow; a recent poll by the Levada Centre found nearly half of all Russians want him to step down at the end of his term in six years.

Pussy Riot has used rough punk performances to highlight the ills it sees in Russian society, from Putin's growing authoritarianism to his close relationship with the Orthodox church.

Samutsevich said the trio had not continued writing songs in jail. "The conditions in the pre-trial detention centre aren't really creative," she wrote. "For the next one and a half years, we'll have to continue to 'take a break' from our concert creative work."

She said the women's future in the group was in question. "Right now it's hard to say what we'll do when we're free. Of course, I'd want to continue in the same form of musical performances that we started with, but will our changed conditions, because of our arrest, allow that? So far I don't know.

"What I can say for sure is that we still madly want changes in Russia – toward anti-authoritarian leftist ideas. We, along with many citizens of our country, are burning even more with the desire to finally take from Putin his monopoly on power, since his image no longer seems so total and terrible," she wrote. "In fact it is just an illusion, created by his spin doctors on government television channels."