Union leader Yaakov Seltzer, head of the employees union told news agencies that Sharon might have to bring his own sandwiches to work, since members were taking strike action.
Unions had been angered by budget cuts announced by Sharon, enabling the Israeli government to take control of pension funds.
Aljazeera.net tried unsuccessfully to be transferred to Sharon's office, after calling the PM for a comment. The receptionist denied that Sharon had problems receiving phone calls.
''If the treasury does not renounce these projects, we will strengthen our action. The prime minister will have to bring his own sandwiches from home to work as we won't be serving food or drinks'' Seltzer told Israeli radio.
The trade Unions staged small strikes to protest against the proposals last week, causing disruption to Israel's ports and airports.
Further industrial action could be called on 3 November by the Histadrut union, if talks with the finance ministry do not break the deadlock.