Zia and bitter rival Sheikh Hasina, also a former prime minister of Bangladesh, have been hounded by the army-backed interim authority in a crackdown on corruption that has so far netted more than 160 senior politicians.
Hasina, who faces charges of extortion and murder at home, has effectively been barred from returning to Bangladesh after making a private visit to the US. She is presently in London.
She will start her journey home from London on a confirmed commercial flight Sunday despite a reported ban on her return, a close aide said.
The two women, who do not speak to each other and had been considered top contenders in any election, are widely blamed for many of the nation's problems.
Zia ended her five-year tenure as prime minister in October, replaced by an army-backed authority that says it is determined to clean up politics ahead of the promised, but as yet unscheduled parliamentary, election.
Former army brigadier Hannan Shah, a former minister and a member of Zia's Bangladesh Nationalist Party (BNP), met Zia late on Friday in Dhaka.
"She is not going into exile but trying to restructure the party," Shah said. "The chief strongly opposes going abroad. She would rather face the law within this country, if it comes to her."
Zia on Saturday visited Tarique who is in jail now awaiting trial in an extortion case.
Abdus Sobhan Golap, Hasina's close aide said: "Our leader will fly as per schedule."
Hasina is scheduled to board a British Airways flight at Heathrow airport to arrive in Bangladesh on Monday, he said.