Pirates have targeted two commercial ships off the coast of Nigeria in two separate incidents less than five hours apart, according to authorities.

Both incidents took place on Saturday and occurred between 40nm to 50nm south-south-west of Bonny Island, according to reports from the IMB Piracy Reporting Centre.

In the first incident around eight armed pirates in a speed boat chased an unnamed container vessel while it was underway.

Reports say the alarm was raised, the ship security alarm system (SSAS) was activated and all non-essential crew retreated to the ship’s citadel.

As the pirate boat closed with the container ship the vessel began to take evasive manoeuvres.

The vessel had also deployed ‘hardening’ measures and the pirates were unable to hook their ladder to ship’s side, the IMB said.

The attackers are said to have eventually broken off their attempt to board and the container ship was met by a Nigerian Navy escort.

In the second incident around 10 pirates in a speed boat, armed with automatic weapons, are reported to have chased and fired upon a reefer vessel while it was also underway.

“The armed guards onboard the vessel returned fire, resulting in the pirates aborting the attach and moving away. All crew safe. Vessel sustained minor damage due to the firing,” the IMB said.

“There have been at least 75 recorded piracy incidents in the Gulf of Guinea in the six months to February 2018, most of them off Nigeria,” said UK-based security consultancy Grey Page.

“Attacks typically involve small boats coming alongside while the pirates attempt to board.

“The attackers are often armed and violent and in the most serious cases seafarers have been seized as hostages.”

Grey Page said all waters in and off Nigeria and in the wider Gulf of Guinea should be seen as dangerous.

With most attacks take place at night, vessels are advised to minimise time spent in anchorages and to avoid slow steaming while underway.