Intelligence agencies have completed a report into the preliminary investigation into the attack which found the involvement of the Tehreek-i-Taliban Pakistan's Sindh chapter in the assault on the naval dockyard on September 6, the Dawn reported.
The attackers intended to destroy the navy workshop and other key installations in the vicinity, according to the probe report which added that timely action by the Naval commandos had foiled the attempted terror attack, it said.
Citing the report, the paper said that TTP's Sindh chapter had penetrated into various departments of the provincial government.
The report said that 21 suspects, including 14 servicemen, have been arrested in the attack case.
Three government employees were also arrested from Larkana district and two from Jamshoro district of Sindh.
Three armed forces personnel including a Navy officer were earlier arrested from Quetta, Balochistan.
During questioning, the detained suspects disclosed that all involved persons had planned to escape to Afghanistan after conducting the attack.
The attack on the Naval Dockyard was thwarted by naval commandos. One sailor and two attackers were killed, while four were captured alive.