Anwar, the leader of the People’s Justice Party (PKR) received a royal pardon for a sodomy conviction, which was widely viewed as trumped up.
"I am here as a concerned citizen to give complete support to manage the country on the understanding that we are committed to the reform agenda, beginning with the judiciary, media and the entire apparatus," he said in a news conference at his home.
Read more:Malaysia election: People were 'disgusted with government's corruption'
Malaysians 'demand change'Anwar thanked Malaysian voters who he said "stood by the principles of democracy and freedom" before adding that he would take some time off before resuming his political career.
Despite being in prison, the 70-year-old joined forces with Mohamad in a four-party alliance to win a shocking victory in the May 9 elections, ending more than 60 years of rule by the Basiran National coalition and ousting Prime Minister Najib Razak.
One-time protegeAnwar was once a protege of Mahathir, who was previously prime minister from 1981 to 2003. The two had a falling out over the handling of the 1997 Asian financial crisis, resulting in Anwar being sacked as deputy prime minister.
Anwar was then sentenced to five years in prison for sodomy and corruption in what he and rights groups called a politically motivated attack.
He was freed in 2004, but then jailed again for five-years in 2015 for sodomy, in what his supporters considered an attempt by Najib to end his political career.
Anwar, 70, was set to be released from jail at the beginning of June, but without the royal pardon he would have faced a five year ban in politics. The pardon now paves the way for him one day becoming prime minister.
On Wednesday, he said he had buried the hatchet with his one-time rival saying "it was a long time ago."
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Post-election power playsMahathir, the oldest head of government in the world at 92, was sworn in as prime minister on Thursday. He has agreed to eventually hand power to Anwar.
However, on Tuesday the prime minister said he planned to stay on for "an initial stage, maybe lasting one or two years."
"I will play a role in the background even when I step down," he said.
Meanwhile, there are signs of early tensions between Mahathir and Anwar's PKR, which won the most seats in the four-party alliance that ended Basiran National's entrenched rule. PKR is demanding a proportionate number of positions.
"I expect him to play the same role as the leaders of the other three parties. There will be no special powers given except as are given to ministers or deputy ministers or deputy prime ministers," Mahathir said.
So far only three ministers have been appointed, in addition to Mahathir and Anwar's wife, Wan Azizah Wan Ismail, as deputy prime minister.
Read more: Malaysia's new law against 'fake news' snares second opposition leader
Separately, Malaysia and six countries are investigating defeated prime minster Najim over corruption at the state fund 1MDB. He has been barred from leaving the country.
mm, cw/aw (AFP, dpa, AP, Reuters)
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