The government has insisted it will not make a ransom payment to Somali pirates who have kidnapped a British couple.
Paul and Rachel Chandler, aged 59 and 55 and from Kent, were taken hostage by gunmen as they sailed their yacht in the Indian Ocean early on 23 October.
A ransom demand of $7m (£4.3m) was made in a phone call to the BBC on Friday.
The Foreign Office said the couple were "blameless tourists" but said no payment would be made nor advice given to relatives on how to make a payment.
A spokesman for the Foreign Office added: "We are aware of reports that a ransom demand of $7m has been made. [Her Majesty's Government] HMG's policy remains clear: We will not make substantive concessions to hostage takers, including the payment of ransoms."
The Chandlers, of Tunbridge Wells, had been travelling to Tanzania from the Seychelles. Their yacht was later found in international waters.
In the phone call to the BBC one of the pirates said: "If they do not harm us, we will not harm them - we only need a little amount of seven million dollars."
Rob Macaire, British High Commissioner, Kenya, told the BBC: "We are not in direct contact with whoever is holding the Chandlers.
"Our main concern is to make them understand that what they are doing is entirely unjustified and that they should release the Chandlers immediately and unconditionally."
Armed pirates boarded the Chandler's yacht, the Lynn Rival, in the Indian Ocean while they slept.
Mr Chandler's brother-in-law Stephen Collett has previously insisted that the couple are "not rich people" and that most of their money is tied up in their yacht.
In an interview with the BBC, a local Somali official said through a translator that he believed a number of groups were involved in handling the couple.
He said the pirates had "many cars" and had hired extra people to help them.
He added that divisions had emerged among the groups and while all wanted a ransom paid, others wanted the release of pirates recently detained by European Union warships.
Earlier, the BBC's East Africa Correspondent Will Ross said in previous cases pirates had begun negotiating with an extremely high figure, and then settled for far less.
In a phone call on Thursday, the Chandlers said they were first moved from their yacht to a container ship, the Kota Wajar, which had also been seized by the pirates.
It is thought they were then moved to another ship anchored off the eastern coast of Somalia on Friday.
The BBC's security correspondent Frank Gardner has been told by Whitehall officials that the government has appointed a hostage negotiator who is on standby to deal with the case.
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