"I want to assure you, in unequivocal terms, that we are firmly determined to discharge our responsibilities in holding the polls, as announced, by December 2008," he said late on Sunday in a televised speech to the nation.
Ahmed vowed that polls could be held "even before" the deadline as soon as the government prepares a new voter list and introduces electoral reforms after talks with the country's various parties.
"The talks with the political parties will begin on September 12 and continue until November," he said.
The move comes as the leaders of the two main parties, former prime ministers Khaleda Zia of the Bangladesh Nationalist party (BNP) and Sheikh Hasina Wajed of the Awami League, are under arrest on corruption charges.
The two women held power alternately from 1991 to 2006, but have been accused by authorities of blatant corruption and pushing Bangladesh's fragile democracy to the brink of collapse.
"We welcome it. It's a right move and we feel assured."
Awami League acting president
The government came to power on January 11 after months of deadly protests by opposition parties over alleged vote-rigging by the BNP, leading the president to cancel planned national polls and impose a state of emergency.
It has since launched a massive anti-corruption crackdown, arresting nearly 160 high-profile political leaders including Zia and Sheikh Hasina - the 'battling Begums' - and banning protests and rallies.
Major political parties welcomed the easing of restrictions.
"We welcome it. It's a right move and we feel assured," Zillur Rahman, Awami League acting president, said.
"It will pave the way for restoration of democracy in the country,' said Abdul Mannan Bhuiyan, the leader of the 'reformist' faction of the BNP.