A spokesman for the pirates holding Paul and Rachel Chandler said the kidnappers were torn between asking for a ransom or the release of their comrades.

The couple, from Tunbridge Wells in Kent, were captured more than a week ago as they sailed from the Seychelles towards Tanzania in their yacht, the Lynn Rival.

The pirates have demanded a $7m (£4.2m) ransom for their release but their family’s repeated assertion that there is no money to pay it may have prompted the pirates to consider other options.

"You know there are seven pirates who were arrested by the foreign forces after the attack, some of us are insisting to exchange the two with their friends while others just want to get ransom," pirate spokesman Abdi Yare said.

The seven were rounded up in a joint operation by the European Union Naval Force Somalia (EU NAVFOR) after they tried to hijack a French fishing vessel 350 nautical miles east of Mogadishu on Tuesday.

The pirates approached the boat in two fast attack skiffs and opened fire, but were repelled by its onboard security team.