Ms Zia says that the run-up to the vote must be fair
The military-backed interim government in Bangladesh has announced that general elections will be held as planned on 18 December.
It said it had decided to keep to the date after failing to persuade political parties to drop their differences over the schedule.
The Bangladesh Nationalist Party (BNP) has threatened to boycott the poll unless emergency rule is lifted.
Its main rival, the Awami League, has said it will take part in the vote.
The government also refused to suspend the state of emergency which was imposed in January 2007 after months of unrest.
The BBC's Mark Dummett in Dhaka says a BNP boycott would be a serious blow to the government's pledge that the elections will be the fairest in the country's history.
Without the participation of former Prime Minister Khaleda Zia's party, many will doubt its legitimacy, our correspondent says.
The BNP and its allies won a two-thirds majority in the last elections in 2001 and the party remains popular - but during the two-year rule of the caretaker government it has been seriously weakened.
Many of its leaders, including Khaleda Zia and her two sons, were accused of corruption and jailed.
She was then freed on bail, but about 50 others are still behind bars.
Bangladesh's other main party, the Awami League, was less affected by the anti-corruption drive, even though its leader Sheikh Hasina was also jailed for a while.
It agreed to participate in the elections and has for some time been confident of winning, our correspondent says.