Somali pirates have released a Bangladesh-flagged vessel and its 23-member crew after a ransom was reportedly paid.

The MV Abdullah was carrying coal from Mozambique to the United Arab Emirates (UAE) when it was hijacked off Somalia's coast about a month ago.

The pirates alleged that they received $5m (£4m), but there is no independent confirmation of the claim.

A spike in hijackings has been reported off Somalia's coast in recent months.

More than a dozen vessels have been targeted since late November.

Security experts said a security vacuum had developed off Somalia's coast after foreign navies patrolling its waters turned their attention to the Red Sea, where Yemen's Houthi rebel group have been attacking ships.

Between 2005 and 2012, pirates off the Horn of Africa raked in between $339m and $413m by holding crew members hostage and demanding ransom payments, the World Bank has estimated.

Reuters news agency reported that it was told by two pirates that a $5m ransom was paid for the release of MV Abdullah and its crew.

"We checked whether the money was fake or not. Then we divided the money into groups and left, avoiding the government forces," Reuters quoted one of the pirates, Abdirashiid Yusuf, as saying.

The vessel's owner, the KSRM Group, said the vessel and its crew were freed following negotiations.

"We struck a deal with the pirates," Mizanul Islam of SR Shipping, the group's maritime arm, told AFP news agency.

"We cannot say more about the money," he said, adding: "All the crew are safe and secure."

The ship has since sailed to UAE, escorted by two warships.