The penalties were provided for under new sections of Brunei's Shariah Penal Code. Sultan Hassanal Bolkiah instituted the code in 2014 to bolster the influence of Islam in the oil-rich monarchy of around 430,000 people, two-thirds of whom are Muslim.
Even before 2014, homosexuality was already punishable in Brunei by a jail term of up to ten years. The first stage of the Shariah Penal Code included fines or jail for offences such as pregnancy out of wedlock or failing to pray on Fridays.
But under the new laws - which apply to children and foreigners, even if they are not Muslim - those found guilty of gay sex could be stoned to death or whipped.
Adulterers risk death by stoning too, while thieves face amputation of a right hand on their first offence and a left foot on their second.
The law change, which came into force this week has faced fierce criticism from the international community.
Joining in the condemnation, Dr John Sentamu wrote on Twitter: "The criminalisation of sex between two consenting adults is, in my book, repugnant to natural justice!
"Therefore, it is a crime against the innocent!
"What the State of Brunei has just passed as 'law' must NEVER be implemented in our Global Village! PLEASE GOD!!"
(Additional reporting from Press Association)
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