State control is deepening in Southeast Asia's second-largest economy. Harsh censors and restricted freedom of expression have always weighed on Thailand's human rights record, but developments over the past month now suggest an intensified level of state control — a fresh development on top of the nation's delayed return to democracy.

A general view at the Damnoen Saduak Floating Market in Bangkok. Isa Foltin / Getty Images

In the Kingdom of Thailand, the prime minister manages government affairs but the centuries-old monarchy still remains a deeply revered institution — walls of nearly every establishment and household have at least one image of the king. And any perceived insult or defamation of the monarchy is punishable by up to 15 years in prison, according to the country's lese-majeste laws that are among the world's strictest. Meanwhile, those who express opposition to military rule — the current form of government and one that has been a staple throughout the nation's 19 army coups since 1932 — can get slapped with sedition charges that carry a seven-year jail term. Earlier this month, a letter from the Ministry of Digital Economy and Society banned Thais from any kind of interaction with three well-known critics: journalist Andrew MacGregor Marshall, historian Somsak Jeamteerasakul and academic Pavin Chachavalpongpun. Citizens who follow, contact or share content from the trio on the internet could be violating the Computer Crime Act, the directive said. The three men, who remain respected in international circles, have written extensively about the monarchy's failure to follow democratic governance and a need for the royal institution to fundamentally reform its powers. Among the contentious topics discussed in their writings are the country's Privy Council, an advisory body handpicked by the king that oversees key military and judiciary appointments reportedly to protect royal interests, and a lack of transparency over the royal family's wealth. The Crown Property Bureau manages the monarchy's investments and is the country's largest corporate group with assets valued between $37 billion to $53 billion, according to media reports. However, it is subject to the king's control.

Marshall, Jeamteerasakul and Chachavalpongpun left the country years ago and face arrest if they ever return for their scrutiny of royal practices. As a result of the ban, Marshall and Chachavalpongpun told CNBC that their respective social media following spiked dramatically, but that they remain concerned about the safety of their families back in Thailand. While the international community has long reprimanded Bangkok for detaining and arresting citizens under lese-majeste and sedition charges, the public targeting of Marshall, Jeamteerasakul and Chachavalpongpun was unusually aggressive, experts said. "The recent ban is even more heavy-handed than usual and reflects discomfort with criticism of the monarch," said Christian Lewis, Asia associate at political risk consultancy Eurasia Group. Many believe King Maha Vajiralongkorn, who took over the throne in December following the death of his father King Bhumibol Adulyadej, plays a key role behind Bangkok's increasing autocratic stance. International media have widely described the former crown prince as a playboy who spent much of his time abroad. Before signing the new constitution on April 6, King Vajiralongkorn made several changes that analysts believe enhance his royal powers, such as naming the monarch as the key arbiter in times of constitutional upheaval. That legally places the king at the forefront of potential political disputes, to which Thailand is no stranger, and sets the stage for the monarchy to intervene in politics, noted Joshua Kurlantzick, senior fellow for Southeast Asia at the Council of Foreign Relations. Thai officials did not respond to CNBC's request for comment. "The new reality in Thailand is a move toward enhanced state absolutism, likely reflecting the preferences of the new sovereign, as implemented by the junta," said Paul Chambers, lecturer at Naresuan University in the Thai province of Phitsanulok. British-born Marshall, a former Reuters deputy editor who resigned from his role in 2011 in order to self-publish an online exposé of the Thai monarchy based on 3,000 leaked U.S. diplomatic cables, alleged to CNBC that it was King Vajiralongkorn who ordered the ban on Jeamteerasakul, Chachavalpongpun and himself.

Thailand's King Vajiralongkorn after signing the military-backed constitution in Bangkok on April 6, 2017. LILLIAN SUWANRUMPHA / AFP / Getty Images