Image copyright Reuters Image caption Crowds of well-wishers gathered outside the hospital

The health of Thailand's King Bhumibol Adulyadej, the world's longest reigning monarch, has "overall not yet stabilised", the palace has said.

On Sunday the palace announced that the king was in an unstable condition after receiving haemodialysis treatment.

King Bhumibol, 88, is widely revered, and a crowd of well-wishers have gathered outside Siriraj hospital.

Prime Minister Prayuth Chan-ocha cancelled an official engagement to meet the Crown Prince.

A palace statement late on Wednesday said the king's "blood pressure lowered and breath quickened".

It said his liver and kidneys were not working properly and he remained on a ventilator.

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The unprecedented concern over his health has caused stocks and Thailand's currency, the baht, to tumble.

The Stock Exchange of Thailand closed down 2.5%, its lowest since the end of May.

A government spokesman urged people to rely on official announcements for updates on the situation, rather than on "uncorroborated information in social media circles".

Image copyright Reuters

Pink, for luck - Jonah Fisher, BBC News, Bangkok

A day of rumour and speculation ended with a statement from the Royal Household Bureau.

Three days after it was first announced that the king was in what's being called a "not stable" condition came confirmation that he was not doing any better.

Outside the hospital hundreds of well-wishers, many of them dressed in pink for luck, prayed for King Bhumibol.

Having first acceded to the throne 70 years ago he has been a source of stability and unity for a much changed and still deeply divided nation.

King Bhumibol is the world's longest serving monarch, having acceded to the throne when his brother died in 1946.

During his seven decades on the throne the king, who is seen as a unifying force, has intervened when events threatened to plunge Thailand into crisis.

Amid increasing concerns about his health in recent months, the Royal Household Bureau has issued more frequent bulletins.

Earlier this month, a statement said the king was recovering from a respiratory infection.

Image copyright Reuters Image caption Hundreds of Thais chanted prayers outside the hospital for his recovery

Thailand's strict lese majeste laws mean public discussion of his health and succession plans are not permitted, and are punishable by lengthy jail terms.