Thailand's Princess Ubolratana has apologised for causing "problems" after her shock prime ministerial bid last week was quashed. Picture: AP Photo/Kin Cheung

Bangkok - Thailand's Princess Ubolratana, King Maha Vajiralongkorn's elder sister, has apologised for causing "problems" after her shock prime ministerial bid last week was quashed.

"I'm sorry that my sincere determination to work for the country and the people has caused problems that shouldn't have happened in this day and age," the 67-year-old princess wrote on her Instagram page late Tuesday.

She ended her post with the hashtag #howcomeitsthewayitis.

The princess's apology came a day after the Election Commission disqualified her candidacy for the March 24 general election, the country's first election in eight years and the first since the 2014 coup.

Although the commission did not provide an explanation for her disqualification, it is widely believed that the decision derived from the king's statement calling her involvement in politics unconstitutional and inappropriate mere hours after her unprecedented nomination was announced on Friday.

The king's decree seemingly disproved previous assumptions that the palace's antagonism towards the controversial Shinawatra family, who are behind the party's nomination and maintains a close friendship with Ubolratana, had ended.

The princess's apology also came amid the commission's deliberations on whether to file for the dissolution of Thai Raksa Chart Party with the Constitutional Court.

If the party is dissolved, the pro-junta party could gain a further advantage in the upcoming election, analysts said.

dpa