India on Thursday accused Pakistan of not doing enough to punish the men who plotted the 2008 militant attacks on Mumbai, as the city prepared to mark the second anniversary of the bloodbath.
A senior Pakistan diplomat confirmed to AFP that an official diplomatic message was delivered to the embassy in New Delhi urging Pakistan to "fulfil its obligation and commitment" to bring the plotters to justice.
Ten gunmen launched coordinated attacks on luxury hotels, a railway station, cafe and Jewish cultural centre on the evening of November 26, 2008, starting a 60-hour siege that left 166 people dead.
Nine of the gunmen were killed, and the sole survivor has been sentenced to death in an Indian court.
The letter accused Islamabad of stalling over the trial in Pakistan of seven suspects accused of plotting the attacks.
"New Delhi expresses regret for not receiving feedback on issues raised by it," the letter said.
The suspects on trial include the alleged mastermind of the attacks, Zakiur Rehman Lakhvi, and Lashkar-e-Taiba (LeT) operative Zarar Shah.
New Delhi and Washington have both blamed the Mumbai attacks on the Pakistan-based LeT.