Leader of Thai Raksa Chart party Preecha Pholphongpanich, right, hands a paper with a picture of Princess Ubolratana at election commission of Thailand in Bangkok, Thailand, Friday, Feb. 8, 2019. The political party has selected the princess as its nominee to serve as the next prime minister. (AP Photo)

Bangkok (dpa) - Thailand's Princess Ubolratana, King Maha Vajiralongkorn's elder sister, was on Friday nominated as prime minister for the March 24 general election by Thai Raksa Chart, a party founded by allies of former prime minister Thaksin Shinawatra.

It is the first time in the country's history that a member of the royal family is to run for office and become directly involved in politics.

"The Thai Raksa Chart Party is highly honoured by Princess Ubolratana's bid for the party's prime ministerial nomination," the party said in a statement.

"The princess has worked to promote Thailand's tourism industry for up to 10 years. She deems it appropriate timing to volunteer to work as a prime minister to help the people and the country," the party added.

The 67-year-old princess officially relinquished her royal title when she married a US national in 1972. She returned to Thailand in the late 1990s after getting a divorce. Although her formal title was not restored, she is regarded and treated as royalty by the Thai people.

Ubolratana is also known as a long-time friend of the Shinawatra family, which has an influence on the upcoming election through its proxy political parties without fielding a direct family member this time.

Friday was the last day political parties could nominate their prime ministerial candidates. Each party is allowed to nominate up to three people.

The princess's prime ministerial bid was heavily rumoured earlier this week but there was no confirmation until Friday.

Ubolratana has yet to make any comment on the nomination. But she posted photos on her Instagram page saying she was in the northern city of Chiang Mai, along with the cryptic message "we will walk together."

Political analysts see the shocking move as a further political complication in the South-East Asian country ahead of its first election since the 2014 coup and return to democracy.

"Thai politics' faultline has been drawn on the monarchy. [Now] the era of the so-called 'monarchy above politics' is officially over," said Pavin Chachavalpongpun, a political science lecturer at Kyoto University.

Soon after the princess's nomination, Thai Prime Minister and junta leader Prayut Chan-o-cha announced that he accepted the pro-junta Phalang Pracharat Party's nomination as its prime ministerial candidate.

"I have thoroughly considered the party's policies and I deem that they can further the programmes the [military regime] has initiated... so I accept the Phalang Pracharat Party's nomination as a prime minister candidate," Prayut said in a statement.

"I maintain that I have no intention to prolong my power in office. I only want to work for the benefits of the country and the people," he added.

The 64-year-old general staged a coup in May 2014 after months of massive demonstrations against the Yingluck Shinawatra administration, becoming the country's prime minister in August of the same year.

Initially planning to stay in power for only one year, the junta postponed the election date at least five times, citing the need to fulfill its reforms and oversee a smooth royal succession.