Mumbai, Feb 22 (IANS) The periscope of Indian Navy’s submarine INS Sindhughosh was damaged after a fishing boat hit it during an exercise off Mumbai coast, a naval official said Sunday.

“In a minor incident off the west coast, a fishing vessel has hit the periscope of the submarine which was involved in an exercise,” the Navy official, adding the incident occurred happened in the night between Thursday and Friday.

“The exercise was being conducted in pitch dark conditions as required by the exercise prerequisites,” he said.

Official sources said the exercise required the submarine to be under water near the coast with no lights or sound while there are many fishing vessels around.

“One of them hit the periscope,” the official said.

The official added no major damages to the submarine have been reported.

“It has since returned to Mumbai dock yard and repairs would be effected soon,” the official said.

“All relevant authorities have been kept informed by Naval headquarters.”

This is not the first accident involving the submarine which is the lead ship of her class of diesel-electric submarines.

In January 2008, it collided with a foreign merchant vessel – MV Leeds Castle. The submarine was submerged and had its radars off and periscope down when it slammed into the merchant vessel

In January 2014, Sindhughosh ran aground at the naval harbour in Mumbai due to the low tide. The submarine was re-floated and did not suffer much damage. At the time of the incident, it was fully armed, carrying its entire compliment of 70 personnel, all of whom were safe.

It had also suffered some damage in August 2013 when blasts ripped through the torpedo compartment of the INS Sindhurakshak while the submarine was berthed in Mumbai harbour.