Attackers have boarded a ship off the coast of Somalia after firing machine guns and rocket-propelled grenades at the vessel, according to a UK maritime agency.

Greek shipping company Latsco Marine Management confirmed the attack on a ship carrying gasoline, saying all the ship's 24 crew were "safe and accounted for" and "we remain in close contact with them".

The crew have taken shelter in the ship's fortified safe room, Reuters news agency quotes an official from maritime security company Diaplous as saying.

European Union naval forces operating in the area have been asked for assistance, Reuters says.

The United Kingdom Maritime Trade Operations (UKMTO) says the raid happened about 560 nautical miles south-east of the Somali town of Eyl.

"The Master of a vessel has reported being approached by one small craft on its stern. The small craft fired small arms and RPGs towards the vessel," UKMTO said in a statement.

Private security firm Ambrey said the attackers were probably Somali pirates, who have been active in the region in recent days.

According to Latsco, the attack on the Malta-registered vessel occurred at around 11:48 local time (08:48GMT).

"[Latsco] has activated its emergency response team and is coordinating with the relevant authorities to ensure the continued safety and welfare of the crew," it said.

The vessel, named Hellas Aphrodite, was built in 2016, and was en route from Sikka, India, to Durban, South Africa, it said

The attack comes amid a resurgence of piracy in the region, which had declined after peaking more than a decade ago.

There were at least seven reported incidents last year, and several fishing vessels have already been seized by pirates this year, according to the International Maritime Bureau.