The Sultan of Brunei, Hassanal Bolkiah, is to implement a form of strict Islamic Sharia law across Brunei next month, rejecting foreign criticism of the move.

New legislation will phase in a version of Sharia law that will introduce penalties of amputation for theft, stoning for adultery and flogging for homosexual acts.

The reigning Sultan Bolkiah, 67, called on the whole of Brunei's diverse population to unite and support the new legislation.

He said that the laws, to be implemented next month, were a "great achievement for the country, and not a backward or old-fashioned step."

Human rights groups have condemned the move but Bolkiah stated that "people outside of Brunei should respect us in the same way that we respect them."

"Brunei is showing its feudal characteristics as an 18th-century state rather than an important member of a regional Southeast Asian economic and social consensus in the 21st century," said Phil Robertson, deputy Asia director at Human Rights Watch.

The south-east Asia nation of Brunei holds a population of approximately 440,000, of which a third is non-Muslim - predominantly Christian or Buddhist Chinese.

In a nation where dissent is rare, some Bruneian citizens have taken to the internet to voice their concern at the new laws.

However Bolkiah, who was crowned in 1968, warned dissenters that they can "no longer be given the liberty to continue with their mockery" and hinted that they could be charged with slander.

Brunei, despite being an autocratic state, is ranked fifth in the world for per capita GDP, one above the United States.

Bolkiah holds a personal wealth of £11.9bn ($20bn), making him one of the richest men in the world, and lives in a 1,800-room palatial residence.