Al Jazeera's Roza Ibragimova, reporting from Bishkek, said Otunbayeva used the address to explain why the interim government decided to let Bakiyev leave, accusing him of bringing the country to the brink of civil war.
"She said that he had become a source of instability ... and they could no longer tolerate that," our correspondent said.
Days of turmoil
Bakiyev fled to neighbouring Kazakhstan on Thursday, ending days of turmoil that disrupted US military flights through a Kyrgyz air base.
"We had an opportunity to take him by force but didn't want to cause further violence," Otunbayeva was reported as saying, stressing that he will face justice after an international investigation is conducted.
"There is no country in the world where he can hide."
Otunbayeva said that she is unsure whether she will run for presidentm, in a vote expected in about six months.
Bakiyev's departure has sharply reduced tensions in the impoverished country after a violent uprising against his five-year rule.
Officials say he is with his wife and two children in the Kazakh city of Taraz, from where he could fly on to Turkey or Latvia.
The interim government called his departure a "deportation" in a statement.
It said that Bakiyev had submitted a request to resign and reports added that Baktybek Kaliyev, a former defence minister and a key Bakiyev ally, had been arrested. These claims were not confirmed by Bakiyev's side.
The interim government also said it would later seek Bakiyev's transfer to a Kyrgyz or international court for trial.
Since being ousted, Bakiyev had been holed up in Jalalabad where he maintains support.
Kazakhstan, which chairs the Organisation for Security and Co-operation in Europe, confirmed Bakiyev had left the country and said it was an important step towards preventing civil war.
It said that joint efforts between themselves and Dmitry Medvedev and Barack Obama, the Russian and US presidents respectively, had allowed for the agreement for Bakiyev to leave the country.
Kazakhstan also said that the move would help to bring stability and the rule of law to Kyrgyzstan.
Al Jazeera's Robin Forestier-Walker, reporting from southern Kyrgyzstan, said: "It is a happy outcome for those who were looking for a diplomatic solution to the problem."
Bodyguards of Bakiyev fired shots into the air on Thursday in an attempt to disperse opposition protesters who gathered to disrupt a rally he was holding in the southern city of Osh.
The shooting take place shortly after Bakiyev took to the podium to address around 2,000 supporters.
"This was a result of Bakiyev venturing out further afield to Kyrgyzstan's second city of Osh," our correspondent said.
"When he went there he was hoping to be greeted by hundreds of thousands of supporters, but instead he was heckled and felt threatened ... he was forced to beat a hasty retreat.
"It was an indication that he was beginning to realise that his continued insistence on holding on to the presidency was creating more destabilisation in the country."
The interim government has called for Bakiyev to surrender, saying he should face trial for "spilling blood" during the unrest last Wednesday that left at least 80 people dead.
Bakiyev has denied ordering troops to fire on the protesters in Bishkek.
Our correspondent also said that the Russian and US governments had pledged funding to the interim government within the last 48 hours or so.
"It is certainly being treated as a government, it is being given that legitimacy. Because it is trying to put the country back on its feet," he said.