Following a week of negotiations which led to the eurozone extending Greece's bailout program for four months, Greece's anti-austerity Prime Minister Alexis Tsipras addressed his Syriza party on Saturday.

"The battle will continue," he told the party's central committee, according to news agency AFP, adding, "Anybody thinking that we are going to go away will be disappointed."

Tsipras, whose party was voted into government in January on a platform of ending the tough austerity measures imposed by Greece's international creditors, also accused Spain and Portugal of taking a hard line in the extension negotiations, saying the governments in Madrid and Lisbon feared for their own survival ahead of elections this year.

"We found opposing us an axis of powers," Tsipras said adding, "Their plan was and is to wear down, topple or bring our government to unconditional surrender before our work begins to bear fruit and before the Greek example affects other countries," he said according to news agency Reuters, alluding to upcoming elections in Spain where the new Podemos movement has topped some opinion polls.

However, in comments published in the Expresso weekly newspaper before Tsipras' speech, Portuguese Prime Minister Pedro Passos Coelho denied that.

'Unacceptable concessions'

Greece's current 240-billion-euro ($270 billion) bailout program had been due to expire on Saturday, but a four-month extension was approved by the Eurogroup of euro zone finance ministers on Tuesday, after the Greek government presented a six-page list outlining its plans for reforms.

Tsipras' government faces the challenge of providing relief for struggling citizens who voted his party in, while also keeping government spending in check. The prime minister portrayed the deal with the Eurogroup as a victory for Greece despite protests in Athens, citing rumblings of dissent from some German parliamentarians even as the Bundestag voted overwhelmingly in favor of agreeing to the four-month extension.

"We have all watched the strong opposition within Angela Merkel's party, which shows that unacceptable concessions have been made to Greece," he said.

Tax avoiders targeted

In an interview broadcast on private Greek television broadcaster Skai on Saturday, Greek Finance Minister Yanis Varoufakis had tough words for tax avoiders in the struggling and debt-ridden eurozone country.

"What interests us is those who have money but who have never paid (tax). They are our target and we will show no pity," Varoufakis said.

Those measures could include a one-off tax on the rich.

"We have committed to balancing our budget. If I have to levy an extraordinary tax then I will do it, but it will only be for those who can pay... We are not going to take money off people who are suffering," he said.

se/gsw (Reuters, AFP, dpa)