David Headley, 55, testified for over five hours on Monday via video link from an undisclosed location in the US and described the role of ISI officers in collaborating with the Lashkar for the terror attack which left 166 people dead in Mumbai.

David Headley said the Lashkar planned the Mumbai attack and said the same group of ten terrorists that attacked Mumbai in November 2008, had made failed attempts to strike the city in September and October the same year.

Headley's testimony would end the ambiguity over the role of Pakistani "state and non-state actors" in the Mumbai terror attack and would take the case to a logical conclusion, said Minister of State for Home Kiren Rijiju, adding, "It will help us."

Home ministry sources have said the Centre will examine the information revealed by Headley on Monday and it may be assembled into a new dossier of evidence to be handed over to Pakistan.

In his testimony, Headley said he joined the Lashkar in 2002 and trained under its leaders Hafiz Saeed and Zaki-ur Rehman Lakhvi, key plotters of the 26/11 attack. India has been asking Pakistan to bring them to justice, but Islamabad has pleaded lack of evidence.

He detailed how he met two ISI officers, Major Ali and Major Iqbal, who connected him to Sajid Mir, a Lashkar recruiter with known links to the ISI. Sajid Mir, was his handler, but he also mentioned "my other Lashkar colleagues".

"It's clear that there is close nexus between ISI and Lashkar that is what has been gathered from the revelation by Headley," said public prosecutor Ujjwal Nikam, who asked Headley over 100 questions.

Mr Nikam said he would question Headley at length on the ISI's role. The prosecutor said only a fourth of the deposition was completed on Monday and it will begin again at 7 am on Tuesday.

David Headley said he came to India eight times before the attacks and once after. He spent two years researching sites, even taking boat tours around the city's harbour and befriending Bollywood stars as part of his cover.