Dhaka Metropolitan Magistrate Rajesh Chowdhury passed the order after the investigation officers of the cases produced them seeking a 10-day remand for each of them.
The court also placed one of their accomplices, Sheikh Sani Mostafa, on a three-day remand in a money-laundering case filed with Gendaria Police Station.
On Monday, the two siblings were arrested from a house in Subadda area of Keraniganj on the outskirts of the capital along with 12 mobile phone sets and Tk 40 lakh.
They remained absconding since law enforcers raided their house at Gendaria in September last and seized 8,072 grams of gold and Tk 5.5 crore in cash, said Imtiaz Ahmed, Deputy Inspector General (Organised Crime) of Criminal Investigation Department (CID), on Monday.
Four money-laundering cases were filed against them, he said.
Investigation showed that the siblings have 22 houses, mostly in old part of the city, 91 bank accounts where they have Tk 19 crore and five cars, the CID official added.