A strategic sale transfers a large stake and management control to a buyer.
For IDBI Bank, the government and LIC hold 60.72%, which is to be sold to a Fairfax subsidiary.
Employees worry about job conditions, pensions and reservation policies.
They have asked for written assurances.
They began a two-day hunger strike on November 2.
The buyer is a subsidiary of Canada-based Fairfax Financial Holdings, identified in coverage as 10955230 Canada Inc.
The sale covers a 60.72% stake, made up of the combined holdings of the government and LIC, for about Rs 52,878 crore, according to The Sunday Guardian.
Management control would pass to the buyer, and the Union Cabinet has approved the strategic sale, according to the same report.
The forum has demanded that the privatisation and strategic sale be withdrawn.
It has also asked that the government keep at least 51% ownership of the bank.
Other demands include protecting existing service conditions and welfare benefits, safeguarding pension and retirement benefits, and continuing reservation policies and industry-level wage revisions.
The forum also wants protection for contractual and outsourced workers and has asked for written assurances on employee rights if ownership changes.
Reports say the forum has also demanded absorption of around 15,000 outsourced and contractual workers.
The forum wants employees to have an option to move to public sector banks while keeping their service records, seniority, pay scales and retirement benefits.
The forum has warned it could intensify its agitation, including a prolonged or indefinite strike, if the demands are not met.
The Joint Platform of Central Trade Unions has urged a halt to the disinvestment and called for an independent investigation and a Parliamentary review, according to reports.
Congress leader Rahul Gandhi has opposed the sale, arguing that privatisation could cost Scheduled Caste, Scheduled Tribe and Other Backward Classes candidates their reservations, according to Business Standard.
IDBI Bank branch, Paravur (file image), Wikimedia Commons, CC BY-SA 3.0