Mourners line up to enter to the Grand Palace to pay respect to Thailand's late King Bhumibol Adulyadej Reuters

Thailand's King Bhumibol Adulyadej breathed his last on 13 October leaving the hearts of his millions of subjects shattered.

King Bhumibol (88), who was seen as a father-figure to the nation, passed away at Siriraj Hospital where he was being treated for his prolonged illness. In spite of the fact that there were regular incidents of political turmoil, coups and violent unrest during his reign, the monarch was highly respected by his people. During decades of political upheaval and rapid development, he was regarded as a pillar of stability and head of an institution central to Thai identity.

Shortly after the palace announced Bhumibol's death, Thai Prime Minister Prayuth Chan-ocha, clad in black suit and tie, addressed the nation and informed people that an heir to the throne had been decided since 1972 and that parliament will soon be informed about the choice by the government. Though the PM did not take any names, it is likely that Crown Prince Maha Vajiralongkorn will succeed his father.

World leaders paid tribute to King Bhumibol Adulyadej and extended their condolences to Thailand. Leaders said that the world's longest-reigning monarch was the champion of his people and expressed fears that his death could bring back unrest in the country.

People mourn for Thailand's late King Bhumibol Adulyadej at the Grand Palace in Bangkok Reuters

United StatesPresident Barack Obama expressed deep grief and said the monarch was a "close friend". The president also paid tribute to the great king saying that his "unflagging devotion" to improving the lives of his subjects was remarkable.

"I had the honour of calling on His Majesty the King during my visit to Thailand in 2012, and recall his grace and warmth, as well as his deep affection and compassion for the Thai people," he said, as reported by Channel News Asia.

King Bhumibol (88), who was seen as a father-figure to the nation. Reuters

UN chief Ban Ki-moon also extended his condolences to the nation. "The Secretary-General expresses his hope that Thailand will continue to honour King Bhumibol's legacy of commitment to universal values and respect for human rights," said his spokesman in a statement, according to the news portal.

Social media is flooded with tribute for the great leader and condolences for the royal family from all corners of the world:

Thailand has beefed up the security as the country prepares for the funeral of the late monarch. The government has also announced that the flags will fly at half-mast at all government buildings and schools in the for 30 days starting from Friday and urged people to refrain from any festivities during the period.