A fully-equipped regional hub for specialist counter-terrorism troops was inaugurated in Mumbai on Thursday, more than three years after the deadly attacks by Islamist gunmen that left 166 people dead.

Indian Home Minister P. Chidambaram opened the new permanent base for the National Security Guards (NSG) in the northern suburb of Marol, a move which is aimed to drastically reduce their response time.

A temporary base set up in 2009 has now been shifted to the new 23-acre (nine-hectare) site in Marol for the 250 NSG commandos.

Regional hubs have also been opened in Kolkata, eastern India, and the southern cities of Chennai and Hyderabad.

Nicknamed the "Black Cats", the NSG is modelled on the British Army's elite Special Air Service (SAS) and the GSG-9, the specialist operations unit of the German police.

The Indian government recommended setting up regional units after the 2008 Mumbai attacks when 10 heavily-armed Islamist gunmen stormed targets including luxury hotels, a Jewish centre and a train station, in a 60-hour killing spree.

NSG troops only arrived in India's financial capital on the morning of November 27 -- some 10 hours after the first shots were fired.