Malaysian authorities have detained a Gambia-flagged cargo vessel suspected of anchoring without authorisation off Perak.

The vessel was intercepted about 4.3 nautical miles southwest of Pulau Jarak on November 8, the Malaysian Maritime Enforcement Agency (MMEA) said in a social media post.

The vessel was detected by the agency's maritime surveillance system in Lumut before enforcement officers were dispatched to conduct an inspection.

The inspection found that the vessel had 21 crew members, comprising 11 Pakistanis, eight Iranians and two Indonesians.

Authorities suspect the vessel committed two offences under the Merchant Shipping Ordinance 1952: anchoring without authorisation from the Director of Marine Malaysia and failing to report its arrival in Malaysian waters.

The vessel's master and chief engineer were taken to the Perak Maritime State Headquarters to assist with investigations. Ship documents were also seized.

The case is being investigated.