Ahmed, who had been hearing the case since he was appointed judge of Rawalpindi's anti-terrorist court no. III in November 2010, was transferred shortly after the last hearing on June 11.
No new judge has been appointed for the court, sources told PTI. The case was placed before a duty judge today, who adjourned it till July 9, the sources said.
The development came just a day after Foreign Secretary Nirupama Rao, who was here for talks with her counterpart Salman Bashir, said she had highlighted India's concerns about a "satisfactory closure" of the Mumbai attacks trial in Pakistan to enable the two countries "to move on with the process of normalisation."
Rao made the remarks while addressing a joint news conference with Bashir at the conclusion of their two-day talks yesterday.
She said the issue of the Mumbai attacks was of "critical importance" to India and she had talked "about matters relating to the 26/11 trial and the pending issues relating to it" during her discussions with Bashir.
The case had been placed before a duty judge at the last hearing scheduled for June 18. On that occasion too, the case was adjourned without any proceedings.
Ahmed's transfer marked the fourth change of the judge conducting the trial of the Pakistani suspects. Ahmed was also conducting the trial of five suspects charged with involvement in the 2007 assassination of former Premier Benazir Bhutto.
He was transferred hours after he issued a permanent arrest warrant for former President Pervez Musharraf for failing to cooperate with investigators probing Bhutto's assassination.
Ahmed had constantly pushed prosecutors to ensure Musharraf's appearance in court. Experts said Ahmed's sudden transfer could affect proceedings in the Mumbai case as any new judge will need time to acquaint himself with the details of the complex trial.
The trial has been marred by delays and technical hitches since proceedings began in 2009. At least one of the three judges who previously heard the case was changed after he received threats from militant groups, sources said.
The seven suspects, including Lakhvi, have been charged with planning, financing and facilitating the November 2008 attacks in India's financial hub that killed 166 people.