New Delhi is expected to send a diplomatic note to Islamabad seeking reply on how Lakhvi submitted two bail bonds worth Rs 1 million each for his release and who stood for the surety.
Official sources said Indian security establishment suspects that ISI might have arranged the surety bonds to ensure Lakhvi's release.
India has already sought the UN's intervention in the release of Lakhvi. India said it was in violation of the norms of the global body and it should raise the matter with Pakistan.
The sanctions measures apply to designated individuals and entities associated with terror groups including al-Qaeda and LeT, wherever located. .
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In the letter by the Indian envoy, it was also mentioned that even the bail amount provided was against the sanctions' committee rule which calls for freezing the funds and other financial assets or economic resources of designated individuals and entities.
The release of Lakhvi had also raised concerns in the US, the UK, Russia, France and Germany with Washington calling for him to be rearrested.
Lakhvi and six others, Abdul Wajid, Mazhar Iqbal, Hamad Amin Sadiq, Shahid Jameel Riaz, Jamil Ahmed and Younis Anjum, have been charged with planning and executing the Mumbai attacks in November, 2008 that left 166 people dead.
Lakhvi, 55, a close relative of LeT founder and Jamaat-Ud Dawa (JuD) chief Hafiz Saeed, was arrested in December 2008 and was indicted along with the six others on November 25, 2009 in connection with the 26/11 attacks case. The trial has been underway since 2009.