Ms Siddiq is accused of obtaining plots of land from her aunt in Dhaka’s diplomatic zone, through “abuse of power and influence”.
She is being tried in absentia with a verdict expected on Monday morning.
Her aunt, Sheikh Hasina, was ousted last year and has since been sentenced to death, although she fled to India before she could be arrested.
Ms Siddiq, her niece, has described herself as “collateral damage” in the new government’s campaign against Sheikh Hasina.
She resigned her ministerial post earlier this year after she was accused of illegally receiving a plot of land from her aunt.
Although an investigation by the prime minister’s ethics adviser did not find “evidence of improprieties”, he said it was “regrettable” that Ms Siddiq had not been more alert to the “potential reputational risks” of the ties to her aunt.
Last week, a group of prominent British lawyers and former cabinet ministers wrote an open letter raising “profound concerns” over Ms Siddiq’s trial in Bangladesh.
Barrister Cherie Blair, who is married to ex-prime minister Tony Blair, Sir Robert Buckland, who served as justice secretary, and Dominic Grieve, an ex-attorney general, wrote that the criminal proceedings against Ms Siddiq were “artificial and a contrived and unfair way of pursuing a prosecution”.
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The lawyers wrote that Ms Siddiq did not have a “proper opportunity of defending herself”.
“She is being tried in her absence without justification and… the proceedings fall far short of standards of fairness recognised internationally,” they said.
The letter was also signed by high-profile lawyers Philippe Sands and Geoffrey Robertson.
They called for the Bangladeshi authorities to put all the allegations to Ms Siddiq’s lawyers “so that she has a fair opportunity to address them”.
