M.A Quayum, the Dhaka city leader of the main opposition Bangladesh Nationalist Party (BNP), was indicted in absentia over the killing last year of the Italian charity worker Cesare Tavella.
Dhaka police have said the murder was part of a conspiracy to smear the secular government and destabilize Bangladesh, which has suffered a series of Islamist attacks on foreigners and religious minorities.
"The court will start hearing the witnesses from November 24th. Five people are now in custody. Quayum and another (indicted person) are still absconding," prosecutor Abdullah Abu told AFP.
Tavella was shot dead in Dhaka's diplomatic zone in September last year by assailants riding on a motorbike.
Bangladesh's elite security force Rapid Action Battalion (RAB) said last week he was killed by a new faction of the Jamayetul Mujahideen Bangladesh (JMB), an extremist group.
But Isis has also claimed responsibility.
The BNP said charging Quayum, who is believed to be living in exile in Malaysia, reflected "the government's malicious intent".
"The RAB DG (director general) said the new-JMB is responsible for Tavella's murder. But today we saw that Quayum was indicted over the murder," senior BNP official Asaduzzaman Ripon said.
"Which one shall we believe as the truth? The government is trying to taint BNP's image internationally by blaming our party men for an incident that we condemned in the first place," Ripon told AFP.
Human rights activist Nur Khan Liton said there should be a fresh investigation.
"Different law enforcing agencies are presenting different versions (of information about the murder)," he told AFP.
"Therefore, it shows the weakness in the charge sheet. We demand reinvestigation to find out the truth."