Social activist Anna Hazare and yoga guru Ramdev will jointly observe a day-long fast at Jantar Mantar here on June 3 to press their demand for a strong Lokpal and to mobilise opinion against black money. Addressing a joint press conference at Gurgaon, they alleged that the government was scared of getting back black money stashed in safe havens abroad and of accepting the Jan Lokpal Bill drafted by members of India Against Corruption (IAC) movement.