Image copyright Getty Images Image caption Princess Ubolratana's bid to run for prime minister was branded "inappropriate"

The sister of Thailand's king has said she is "saddened" by the reaction to her attempted bid to become the country's next prime minister.

Princess Ubolratana was disqualified by the country's Election Commission - who are now also seeking to dissolve the party that nominated her.

Her unprecedented nomination broke with the tradition of the Thai royal family publicly staying out of politics.

King Vajiralongkorn had called her bid "extremely inappropriate".

Posting on her private Instagram account, the princess wrote: "I am sad that the sincere intention to work for the country and us Thais has created a problem that shouldn't happen in this day and age."

The photo she posted - of a scenic garden - also included the hashtag #HowComeItsTheWayItIs.

The announcement that Princess Ubolratana would stand for election sent shockwaves through Thai politics last Friday.

How did the nomination come about?

The US-educated Thai princess relinquished her royal title when she married an American man in 1972.

She returned to Thailand in 2001 after they divorced and has maintained a quasi-celebrity status since - appearing on the entertainment circuit and in music videos.

She was nominated as a candidate for the upcoming general election by Thai Raksa Chart last week - a party allied to divisive former prime minister Thaksin Shinawatra.

The March vote will be the first since the current Prime Minister, Prayuth Chan-ocha, took power in a 2014 military coup - overthrowing the democratically-elected government.

What was the reaction?

The royal family and electoral officials condemned her candidacy almost immediately after it was announced.

The country's election panel said it had excluded Princess Ubolratana because "every member of the royal family comes within the application of the same rule requiring the monarch to be above politics and to be politically neutral".

Image copyright AFP Image caption Thai Raksa Chart's leader Preechaphol Pongpanit defended their nomination

The stance echoed a palace statement, which said the "involvement of a high-ranking member of the royal family in politics... is considered extremely inappropriate".

Analysis by Jonathan Head, BBC News, Bangkok

The row over the princess has reignited old rivalries.

Royalists have come out to accuse Mr Thaksin of once again trying to exploit the monarchy for his own ambitions.

Frustrated supporters of the pro-Thaksin camp, who have been waiting for five years to demonstrate their voting power, fear their side will be tarnished once again as a threat to the monarchy, in order to keep a military-dominated government in power.

This is now bound to be a more heated election campaign.

Read more from Jonathan here.

Thai Raksa Chart's leader, Preechaphol Pongpanit, has said his partydid everything "sincerely, with good intentions", but added: "Above us is His Majesty and the monarchy. We are ready to be investigated."

The electoral commission confirmed on Wednesday that it was seeking to punish Thai Raksa Chart for violating electoral law.

It described the party's nomination of the king's sister as "antagonistic toward the constitutional monarchy" and said it will ask the country's Constitutional Court to consider dissolving them.

Princess Ubolratana's latest post on Instagram will appear to some as a quiet rebuke of the events of the past week.

It's difficult to know just how much direct communication she has had with her brother about this since the fallout - but it's likely she will now have to retreat from political life, no matter how she feels about it.