India's government has moved to ban Indian seafarers from the Gulf of Guinea, citing concerns over piracy.

A circular published by the country's Directorate General of Shipping says pirates have been targeting Indian crew and directs state-approved crewing companies not to hire Indians to work on ships trading solely in the Gulf of Guinea.

"Piracy/armed robbery attacks in the Gulf of Guinea are becoming more violent with a greater tendency to attack, hijack and rob vessels as well as kidnap crew, in the waters of Gulf of Guinea," Capt. Anish Joseph wrote in the circular.

"[I]t has come to the attention of this Directorate that foreign nationals especially Indian seafarers are being selectively targeted during such piracy/armed robbery incidents."

The circular was addressed to shipowners, managers, masters, classification societies and others.

It mentions "two recent incidents" in which Indian crew members appear to have been targeted. It does not mention the incidents by name, but in April, six Indian nationals were kidnapped off a Tomazos Shipping-owned tanker.

In April, the International Maritime Bureau reported year-over-year declines in piracy for the first quarter of 2019, but said the Gulf of Guinea was still a problem area.

The region saw 22 incidents in the first three months of the year, including all 21 of the global reported kidnappings.

Nigeria has the largest coastline on the Gulf of Guinea and is often tied to incidents of piracy. India is also its largest trading partner, according to data from MIT, with Nigeria almost entirely exporting crude oil.

More than 200,000 Indian nationals are employed as seafarers, the third largest contingent worldwide, according to government statistics and domestic media.