India's Ministry of External Affairs summoned Pakistan’s Deputy High Commissioner Mansoor Ahmed Khan to lodge a complaint, while India’s deputy high commissioner visited the Foreign Office in Islamabad to register a similar grievance regarding the delay in proceedings.

Quoting "reliable sources", Indian news publications said Indian officials had sought updates regarding the trial's progress during meetings with their Pakistani counterparts.

The report claimed that Pakistan had postponed the trial of suspects in the Mumbai attacks case several times with the most recent adjournment being the seventh in a row.

It was further alleged that judicial proceedings of the case remained inconsistent due to lack of strong prosecution.

Lashkar-i-Taiba operations commander Zakiur Rehman Lakhvi, Abdul Wajid, Mazhar Iqbal, Hamad Amin Sadiq, Shahid Jameel Riaz, Jamil Ahmed and Anjum have been charged with planning, financing and executing the attacks in Mumbai.

However, since March 3, when terrorists attacked the district courts in Islamabad killing 12 people, including an additional district and sessions judge, progress on the trial slowed down owing to security concerns, sources close to the proceedings said.

The case is related to the killing of 166 people in the Indian city of Mumbai in 2008 by terrorists who New Delhi claims had support of Pakistani suspects.

Meanwhile, Pakistan has called upon the Indian government to expedite the trial process of Samjhota Express attack which had taken place one year prior to the Mumbai attacks.

"Indian Deputy High Commissioner Gopal Baghlay was called for a meeting with Director General South Asia at the foreign office", Pakistan's Foreign Office (FO) spokeswoman Tasneem Aslam told Dawn.

Earlier during a press briefing on July 17, Tasneem had said that Mumbai attack case was under way but also drew attention to the lack of progress in the case relating to the 2007 Samjhota train attack in India in which 70 people, mostly Pakistanis, were killed.

The train was carrying 757 passengers, including 553 Pakistanis, from New Delhi to Lahore via Attari when it was targeted by two low-intensity improvised incendiary devices which caused the carriages to explode near the Shiva village in India's Panipat District.