MUMBAI  - Indian police on Tuesday filed a chargesheet against an alleged key conspirator behind the 2008 Mumbai attacks, which killed 166 people, an official said.

Police officers filed the hefty document to a local court accusing Sayed Zabiuddin Ansari, who was arrested in June, of being a key planner, Joint Commissioner of Police Himanshu Roy told AFP.

"It's been sent," he said, without giving details. He told the Press Trust of India news agency that the chargesheet, at more than 14,600 pages, includes names of 1,783 witnesses and 47 others wanted in connection with the attacks.

Ansari, also known as Abu Hamza or Abu Jundal, is an Indian-born member of the banned outfit Lashkar-e-Taiba. He was detained at Delhi international airport on June 21 when he arrived from the Middle East.

He was allegedly one of the handlers who issued instructions by telephone to the 10 gunmen during the November 2008 attacks. The heavily armed gunmen stormed targets in Mumbai including luxury hotels, a Jewish centre, a hospital and a busy train station.

Ansari, 30, is accused of teaching Hindi to the gunmen, including Mohammed Kasab, the lone survivor now awaiting the death penalty for his role.

Delhi police also filed a charge sheet last month accusing Ansari of involvement in terror activities across India to avenge "atrocities" against Muslims, the PTI reported.

That charge sheet said he had admitted his involvement in the Mumbai attacks during questioning. India blames Lashkar-e-Taiba for training, equipping and financing the Mumbai gunmen with support.

Pakistan has admitted that the attacks were planned partly on its soil, but denies any official involvement. It charged seven alleged plotters behind the attacks in 2009 but has insisted more evidence is needed to convict them.