Freed General Fonseka promises to stay thorn in side of Sri Lankan government

The general, jailed for challenging the president, pledges to campaign to end President Mahinda Rajapaksa's rule
General Sarath Fonseka waves to supporters in Kandy
General Sarath Fonseka, hailed by supporters in Kandy, has vowed to campaighn against the regime that jailed him Photograph: ISHARA S.KODIKARA/AFP/Getty Images

General Sarath Fonseka, the former Sri Lankan army chief released from jail on Monday, has vowed to fight the government in Colombo and to change the nation's political culture.

Fonseka, convicted on charges of graft and engaging in politics while in uniform, was freed by President Mahinda Rajapaksa after more than two years in prison.

He said yesterday that he was determined to join forces with opposition parties – even if the terms of his release prevented him from standing for office.

"I might not be able to contest and vote, but still I can do politics," Fonseka said. "I can educate the people, I can talk to people and have meetings ... And I can do anything else to ensure that this government is thrown away and try to bring another government that will look after the welfare of the people."

Fonseka, widely condemned for his role in atrocities during the 2009 battles against the Tamil Tigers that ended the 25-year civil war, was imprisoned after challenging Rajapaksa for the presidency.

His release may be motivated by a desire to quell international criticism of the government's human rights record before visits by foreign officials and trips by the president over the summer, including one to the London Olympics. A previous trip to the UK ended in controversy when Rajapaksa was forced into a hasty departure after activists sought an arrest warrant for him. Many Sri Lankans regard the former general as a hero. Fonseka's case gained prominence as international scrutiny of the Rajapaksa administration's human rights record intensified. He and his supporters maintain he has been the victim of a political vendetta.

The United States regarded Fonseka as a political prisoner and has repeatedly said he should be freed. In Washington on Friday, the secretary of state, Hillary Clinton, called on Sri Lanka's foreign minister to address human rights issues.

In March, the US sponsored a UN resolution calling on Sri Lanka to investigate abuses alleged to have taken place in the final months of the civil war, a move that strained ties between the countries.

Rights groups say both Fonseka, the president and other senior officials are all implicated in shooting Tamil Tiger fighters as they sought to surrender and ordering artillery bombardments that killed thousands of civilians in the last weeks of the war.

Rajapaksa has repeatedly rejected UN and US criticism on human rights issues and their recommendation that a greater degree of autonomy be granted to the areas of the island where the Tamil minority is concentrated.

Some analysts have raised the possibility that Fonseka's release is in part a political manoeuvre. The popularity Rajapaksa won among the Sinhalese majority after the victory over the Tamil Tigers has faded, and rocketing food prices have dented the government's popularity in the run-up to local elections this year.

The release of Fonseka, who leads a party with seven seats in the 225-member parliament, could further divide an already fragmented opposition.

Fonseka said he had no burning ambition to become president himself and called on opponents of the government to unite to convince voters that change must come.

"It is not going to be that easy," he said. "You have to educate the people about what is right, what is wrong, what the country needs and what has happened to them."

New elections are not due before 2016.