Nigeria's navy on Wednesday retook control of a Singapore-owned tanker carrying a fuel cargo that had been hijacked near Lagos, and its crew of 23 Indian nationals was unharmed, the company said.

The attack was the third in just over two weeks in the Gulf of Guinea and the latest in a rash of such incidents in recent months, with previous hijackings leading to the theft of fuel cargo followed by the release of the crew and ships.

Details were still emerging of the attack late Tuesday, but the crew were said to have taken refuge in a safe room. The gasoline-laden vessel was being escorted to the port of Nigeria's economic capital Wednesday afternoon.

The master of the MT Abu Dhabi sent out a short distress call Tuesday night saying that suspected pirates were boarding the ship roughly 30 nautical miles off Nigeria's coast, said Pat Adamson, a spokesman for Pioneer Ship Management.

Nigeria's navy spokesman, Commodore Kabir Aliyu, said the tanker's location at about 1100 GMT had been established through a tracking device and that a rescue mission had been launched.

The navy vessel closed in on the MT Abu Dhabi at approximately 1400 GMT, said the company statement.

"Command was restored to the master and crew. It is understood that the pirates fled the scene on the approach of the naval vessel. All the ship's crew are reported to be well and unharmed," the statement said.

Aliyu said that no shots were fired and no confrontation occurred as marine forces reclaimed the vessel.

The International Maritime Bureau earlier told AFP that the crew had locked themselves in a safe room when the hijackers boarded.

Adamson said the vessel could have been carrying up to 45,000 tons of gasoline at the time of the attack and it was not clear if any cargo had been stolen.

A security analyst said such attacks near Lagos and other ports in the region are becoming a worsening problem.

"Over the last few months we've seen an increasing number of incidents," said Peter Sharwood-Smith, west African regional manager for risk management consultancy Drum Cussac.

"For the last year and a bit we've been seeing high-level piracy off of Lagos, where they've been targeting tankers to steal their fuel oil cargo," he added.

The latest hijacking comes amid a rise in the number of reported attacks operating in the Gulf of Guinea, which spans the waters off Benin, Nigeria and Togo.

On August 4, suspected pirates attacked an oil cargo vessel sailing off the Niger Delta, killing two Nigerian sailors on board while taking four foreign oil workers hostage. The four have since been released.

Pirates also hijacked and looted two oil tankers off nearby Togo last month. The two ships and all crew members were later freed.

The IMB has repeatedly warned ships plying the Gulf of Guinea off the west coast of Africa to be vigilant and called on authorities to step up patrols, saying last year the region was emerging as a new piracy "hot spot".

The area has seen 37 attacks, including several hijackings, kidnappings and killings, so far this year. Pirates usually target fuel cargo, loading it onto other ships to sell on the black market.

Cyrus Mody of the IMB, who closely tracks the region, said pirate attacks in the Gulf of Guinea had long gone under-reported and that the area had likely seen more violence than recent figures suggest.

As a result, some companies working in the region may not have been fully prepared for the risks involved.

Nigeria and nearby Benin launched joint patrols last year in a bid to combat the problem.