A Greek product tanker was boarded twice by pirate groups over the weekend, but the vessel and crew are reported to be safe.
The first attack occurred on Saturday when the 12,950-dwt New Ranger (built 2007) was boarded while underway 203 nautical miles (376 km) south of Lagos, Nigeria.
Security consultancy Ambrey said the Maltese-flagged vessel had been travelling at 10.4 knots from Lome, Togo, to Douala in Cameroon with an estimated 3.9m freeboard.
The crew mustered in the citadel while the ship performed several turns.
The perpetrators were then reported to have left the vessel.
The next day, the vessel was boarded again, 43 nautical miles south-west of Egina.
Four gunmen gained access to the ship, but were again thwarted when crew reached the citadel.
Attempt failed
Greek security consultancy Diaplous Group said in an update on Sunday: "The pirates have subsequently left the vessel and the incident has ended.
"No crew members were kidnapped in the incident. Crew and vessel are both safe."
AIS showed the vessel at anchor in Douala on Monday morning.
These were the third and fourth attacks in the Gulf of Guinea in three days, following unsuccessful raids on a Minerva Marine suezmax and a Laskaridis reefer.
The first boarding of the New Ranger was in the same area as the attempted boarding of Minerva's 159,000-dwt Minerva Evropi (built 2018) on Friday.
"There has been a surge of incidents in the past five weeks, resulting in an increased risk rating for the Gulf of Guinea high-risk area to critical on 11 November," security company Dryad Global said.
Desperation mounts
"As the rate of failed attacks increases, the perpetrators are highly likely to increase in desperation. This is likely to be because of the increased risk to themselves from naval counter-piracy activity, but from logistical strain also," the company added.
The New Ranger had previously been targeted by pirates in 2011 and 2015.
Diaplous said: "It is assessed that at least two pirate activity groups [PAGs] continue to operate in this area. The PAGs are likely to continue attacks in the area until a successful kidnapping is achieved."
Greek operator Protank Management was not available for further information.
