The Indian navy says it has intercepted a hijacked cargo ship off the coast of Mumbai.

The navy said the Iranian-flagged vessel was spotted last week and kept under continuous surveillance until Sunday, when helicopter-borne marine commandos stopped the ship and took nine people into custody.

Indian officials said Monday the navy had received intelligence that the vessel may have been hijacked and was suspected to be smuggling contraband.

Five Yemenis, two Tanzanians, a Kenyan and a Somalian were on board the vessel. Officials say it is unclear whether those detained are crew members or pirates.

Indian authorities are on high alert against pirates attempting to prey on ships in the eastern Arabian Sea. Indian officials have arrested more than 100 pirates in recent months.

Somali pirates have been operating in the area, more than 2,000 kilometers east of their strongholds on the Somali coast.

The pirates have ventured further and further out to sea to avoid international naval patrols in Somali waters.