Ukraine's interim authorities officially formed a new government on Thursday, with one eye on events in Crimea and another on trying to stabilise the country's disastrous economic situation.

As President Viktor Yanukovych apparently surfaced in Russia, claiming to still be the president and promising a press conference on Friday, Ukraine's parliament set about taking measures to recover some of the billions of dollars they say went missing under his kleptocratic regime.

The new government features some old faces but also has places for a number of people instrumental in the protest movement over the past three months. The new youth minister is Dmytro Bulatov, who was kidnapped and tortured last month by thugs apparently linked to the regime, while the anti-corruption committee will be headed by Tetiana Chornovol, an investigative journalist who was also beaten to within an inch of her life on the outskirts of Kiev in December.

The parliament approved Arseniy Yatsenyuk, a key member of former prime minister Yulia Tymoshenko's party, as prime minister. Yatsenyuk, who was previously foreign minister, was one of the three main protest leaders of the past three months. He began his first speech in office by calling for a minute's silence for those who died in last week's violence.

Yatsenyuk stressed the enormity of the task facing the new government and said joining it could be akin to political suicide, given the tough economic times that are likely to be ahead."I told everyone who is coming into this new government that they are effectively ending their political career by doing so. But we need to think about how we can save the country," Yatsenyuk said.

Oleksandr Shlapak, the new finance minister, said he hoped an International Monetary Fund mission would visit Ukraine next week to hammer out the details of a $15bn package for the struggling economy. The hryvnia, Ukraine's currency, hit a new low on Thursday . It has now lost more than 20% of its value this year.

Speaking in parliament, Yatsenyuk said that the former government had left the country with $75bn of debts. "Over $20bn of gold reserve were embezzled. They took $37bn of loans that disappeared," Yatsenyuk said. "Around $70bn was moved to offshore accounts from Ukraine's financial system in the last three years," he claimed.

Rostyslav Pavlenko, an MP from the UDAR party of former boxer Vitali Klitschko, said that all cases of suspected money laundering and all offshore accounts of former government officials should be investigated, with the aim of repatriating the funds to Ukraine.

"The money in Yanukovych's personal accounts and in the accounts of his family would be enough to cover many current needs of Ukraine," he said. He added that, if the new government did sign the EU association agreement that Yanukovych faltered over, it would be easier to investigate offshore havens and return the stolen money.

Klitschko, who plans to stand in presidential elections on 25 May, called on US and European officials to freeze any accounts suspected of belonging to Yanukovych and his inner circle and return the money to Ukraine.

Switzerland said it was ready to freeze any funds that Yanukovych might be keeping in its banks. The Swiss foreign minister said financial institutions had been ordered to show increased vigilance when dealing with Ukrainian funds. Yanukovych's son Oleksandr, who has amassed a fortune measured in the hundreds of millions of dollars in the past three years, opened a branch of his company, MAKO, in Geneva in 2011.

Meanwhile, investigative journalists are sifting through a haul of documents retrieved by divers from the river near Yanukovych's lavish residential compound outside Kiev. The documents, which are being restored by specialists after being dried in one of Yanukovych's personal saunas, are gradually being posted online, and purport to show multimillion dollar corruption and financial mismanagement.

Yanukovych himself, who has been the invisible man since he fled the capital last Friday night, surfaced on Thursday yesterday with a statement claiming he was still president, and is apparently due to give a press conference in the southern Russian city of Rostov-on-Don on Friday afternoon, Russian media reported.

"On the streets of many cities, there is an orgy of extremism," wrote the president in a statement addressed to the Ukrainian people. "I am certain that in these conditions all the decisions taken [by the parliament] will be ineffective and not carried out. In this situation, I officially declare that I am determined to fight to the end for the implementation of important compromise agreements that will bring Ukraine out of the deep political crisis."

However, even among the president's close allies, he has lost authority after his flight, with the mayors of towns in his eastern heartland describing him as "history", his closest aides fleeing or resigning and Rinat Akhmetov, the oligarch closest to him, saying he is ready to work with the new authorities. Even in Crimea, where the pro-Russian populace has shown little appetite for accepting the regime change in Kiev, there is little sympathy for Yanukovych personally.

There were rumours yesterday that Yanukovych was at a government-run sanatorium outside Moscow, however the location of his press conference, in Rostov, not far from the Ukrainian border, suggests he might have arrived there directly from Ukraine.

"Given that President Yanukovych appealed to Russian authorities with a request to guarantee his personal safety, that request has been granted on Russian territory," a government source told Interfax earlier on Thursday yesterday without specifying the ousted president's location.

The Ukrainian parliament has voted that Yanukovych should be sent to the international criminal court in The Hague, though legal experts have said the court would be unlikely to take on such a case.