Fischer, the 58-year-old economist who headed the Czech Statistical Office, should form a caretaker government by May 5, Prague Radio reported.
His appointment comes three days after the center-right Civic Democrats and the opposition Social Democrats agreed to propose Fischer to run the Czech Republic, which holds a six-month presidency of the European Union by the end of June.
The Civic and Social democrats have a comfortable level of support from lawmakers in Parliament's lower house to guide the government of technocrats until parliamentary elections Oct. 9-10, the radio said.
Fischer replaces Prime Minister Mirek Topolanek, of the Civic Democrats ,whose government resigned in mid-March after losing a confidence vote.
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