She was reacting on Friday to the murder of a BNP leader in Khulna.
Unidentified gunmen opened fire on Khulna BNP's Organising Secretary Sardar Alauddin Mithu at the district's Fultala Upazila on Thursday night.
Mithu died on the spot while his aide Nawsher Ali later died in hospital.
Khaleda has described the killing as "a bid to silence the opposition through intimidation."
The former prime minister slated the ruling Awami League, saying it was on "a mission to kill leaders and activists of anti-government parties."
Referring to Mithu's killing, she said: "This is a cowardly act. They have turned Bangladesh into a graveyard by killing BNP leaders and activists."
She claimed that the government was "carrying out the murders in a planned way by targeting active leaders of the BNP."
The leader of largest opposition party outside parliament warned that the government "would not be able to stay in power by spilling blood and creating panic among people."
"People will revolt,' she cautioned.