No one can be tried for offences under a law that was enacted after the alleged offences took place, the petition said.

Proceeding against Koko under the money laundering act was illegal as per provision of the constitution, since Koko has not been shown arrested in this case, The Daily Star said.

Zia's elder politician son Tarique Rahman has also been charged with corruption. Both brothers were jailed for long and were granted bail on medical grounds. Tarique is currently in London receiving treatment.

Zia was also detained in 2007-08. She lost the December 2008 polls badly and is now leader of the opposition.