AKIPRESS.COM - Thailand's King Vajiralongkorn has denounced as "inappropriate" his sister's unprecedented bid to run for prime minister, BBC reported.
Princess Ubolratana Mahidol, 67, has been nominated as a candidate for a party allied to divisive former PM Thaksin Shinawatra.
Such a move would break with the tradition of the Thai royal family publicly staying out of politics.
Thailand's election is due to take place on 24 March.
It is being closely watched as the first chance for Thailand to return to democracy after five years under military rule.
In a palace statement read out on all Thai TV networks, the king said: "Involvement of a high-ranking member of the royal family in politics, in whatever way, is an act that conflicts with the country's traditions, customs, and culture, and therefore is considered extremely inappropriate."
Hours earlier, Princess Ubolratana defended her decision to run for office, saying on social media that it was her right as a citizen to accept the nomination.