Nairobi - President John Magufuli on Friday suspended the registration of foreign vessels in Tanzania, following the seizure of drugs aboard ships flying his country's flag.
He also ordered an investigation into the 470 vessels currently registered as Tanzanian to determine their activities and whether they are obeying rules.
Magufuli issued the order "following the drug seizures on board Tanzanian-flagged vessels," a statement from the presidency said.
"We cannot allow the name of our country to be tarnished by individuals pursuing their selfish interests," Magufuli said.
Ship owners commonly register their vessels in other countries where fees are lower, rules more lax or oversight less stringent under a system known as "flags of convenience".
Tanzania was found to be the second worst in the world and rated "high risk" by the Paris MoU organisation in its last annual "White, Grey and Black list" ranking the quality of countries' flags for shipping.
In 2012 the Tanzania Zanzibar International Register of Shipping (TZIRS) deregistered dozens of Iranian-owned oil tankers that had used the Tanzanian flag to dodge sanctions.
On Thursday, Magufuli withdrew Tanzania's flag from two vessels seized carrying drugs and arms in recent months.
