A full investigation is being called for into the murder of a British man in Libya, with the authorities there being urged to do all they can to bring the killers to justice.
The families of the man and a New Zealand woman, who were shot dead near the coastal area of Mellitah in the west of the country, have been informed by police, the Foreign Office has said.
Consular officials are providing support.
In a statement, the Foreign Office said it was pressing for a thorough inquiry by the Libyan government into the "appalling crime".
It said: "We are deeply saddened by the murder of a British national and New Zealander in Libya.
"Police have informed their families and consular officials are providing full consular support in Libya and the UK. Our thoughts are with them at this difficult time.
The couple were shot dead near the coastal area of Mellitah in west Libya
"Our charge d'affaires has raised the shooting with the Libyan authorities and we are liaising closely with them on follow-up.
"We call upon the Libyan government to carry out a thorough investigation into this tragic incident and to continue to do all it can to bring to justice the perpetrators of this appalling crime, as it strives to build strong rule of law in Libya."
Sources said the British man was not a teacher, as had been reported.
Mellitah is near the town of Zuwarah and 60 miles west of Tripoli.
The area is home to a large oil and gas complex co-owned by Italian company ENI.
There were also claims that the pair were workers at Mellitah Oil and Gas, which ranks itself as the biggest oil company in Libya.
No-one at the company was available for comment.
The killings come a month after a US teacher was shot dead in the eastern city of Benghazi, after which the Foreign Office said further attacks against Westerners were likely.
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