A Thai princess who was tipped to be the next Queen suffered a massive heart attack last night and is being kept alive in hospital, sources claimed today.

Princess Bajrakitiyabha, 44, was reportedly jogging with her dogs when she collapsed in the Khao Yai National Park in Nakhon Ratchasima province on Wednesday evening.

She is said to have been flown by helicopter from the Pack Chong Nana Hospital to the King Chulalongkorn Memorial Hospital, pictured this morning, in the capital Bangkok in the early hours of Thursday morning December 15.

Medics are reportedly keeping her alive with ECMO treatment and the Prime Minister Prayut Chan-o-cha has flown back early from an overseas trip.

Thai royal watcher Andrew MacGregor Marshall, an author and lecturer, said the prognosis was 'very grim' and that the monarchy - which punishes critics with prison - could be thrown into chaos.

MacGregor claimed the incident has 'huge repercussions' for the Thai monarchy as Princess Bajrakitiyabha was being lined up as the successor to controversial 'crop top king' Maha Vajiralongkorn, who kept a harem of 'sex soldiers' in a hotel in a luxury German hotel during the pandemic lockdown.

Vajiralongkorn has banished his first three male heirs to the United States after a fall-out with their mother and his youngest known male child suffers from severe learning difficulties.

MacGregor said: 'Princess Bajrakitiyabha was initially taken to Pak Chong Nana Hospital where CPR was attempted for hours without success. King Vajiralongkorn rushed to the hospital in a military helicopter.

'Royal sources say the prognosis for the princess is very grim and it's very unlikely she will ever recover. But she could potentially be kept artificially alive via ECMO for weeks or even months while the regime figures out what to do.

'These events have huge repercussions for the Thai monarchy because it was assumed Bajrakitiyabha would be the next monarch or would be regent for her younger half-brother Dipangkorn who has autism and will not be able to reign alone.'

Residents living in the north of Bangkok reported hearing helicopters in the early hours of the morning. They are said to have been one helicopter carrying the stricken princess flanked by two military helicopters.

The Thai palace has not commented on the alleged incident and pliant local media outlets have censored reported on it.