Until Wednesday the authorities maintained that 100,000 people had died in the violence since 1992, although human rights groups have long said the figure exceeded 150,000.
"The number of victims has reached 150,000 and the destruction has reached $40 billion," Butaflika said in a speech on Wednesday.
Islamist fighters unleashed a war after the powerful army cancelled legislative elections that the Islamic Salvation Front (FIS) looked set to win in 1992.
Butaflika is calling for an amnesty to end the long-running conflict, which almost destroyed the oil-rich North African country in the 1990s.
"Algerian people need to be able to accept a general amnesty. I need your support," he said.
The amnesty, which is expected to be put to a referendum later this year, is expected to include rebels and security forces but no details have yet been given.
The authorities say there are between 300 to 500 rebels still active in the country. Security experts say the figure could be as high as 1000.