Viktor Yanukovich will hold a news conference in Russia's Rostov-on-Don at 1700 local time (1300 GMT) on Friday, reports Itar-Tass citing sources close to Ukraine's ousted president.
The site of the event will be announced later, the agency writes.
Yanukovich vanished over the weekend and his whereabouts have so far been unknown, with rumors claiming that he could have fled to Russia, or that he was still in Crimea.
He was reportedly last seen in Crimea.
The new Ukrainian authorities – who came to power following months of violent confrontation – put Yanukovich on an international wanted list on suspicion of involvement in mass killings during the riots in Kiev.
Dozens of people were killed in clashes between armed radical protesters and security forces.
On February 22, Ukrainian MPs voted to oust Yanukovich and hold a presidential vote on May 25.
Ukraine’s parliament, the Verkhovna Rada, held an emergency session and passed a law on the return to the 2004 constitution without the president's approval, saying that the president had removed himself from power.
Yanukovich described the situation as a coup d’etat and said he was not going to resign, as he was a “legitimately elected president.”
On February 23, the parliament voted for its speaker, Aleksandr Turchinov, as acting president of Ukraine.
The Ukrainian leader fled Kiev at the end of the worst week of violence since protests began in November, when he refused to sign an association agreement with the EU.
On Wednesday, Ukraine’s deputy prosecutor general said that the president was still on the country’s soil, without giving any further details.
On Thursday Viktor Yanukovich made a statement that he still considered himself the legitimate leader of Ukraine and warned against an internal military conflict. He also asked Russia to ensure his safety against the actions of “extremists” that took power in Ukraine.
A source inside the Russian authorities told Itar-Tass news agency that his security had reportedly been ensured on Russian territory “in connection with the fact that President Yanukovich appealed to the Russian authorities".