BANGKOK, Nov. 9 (CNA) - Thai protesters dispersed on Sunday night (Nov 8) after being confronted by police and security forces as they marched to the royal offices.

Police had earlier fired water cannon at thousands of protesters who marched from Bangkok's Democracy Monument toward the royal offices to deliver letters demanding monarchy reform from King Maha Vajiralongkorn.

Police used water cannon to try to stop them, but some managed to get through to the area known as Sanam Luang, next to the Grand Palace.

The protesters had marched to the Grand Palace to deliver letters to the king, aimed at telling him how the monarchy should adjust itself in accordance with Thailand's constitutional monarchy system.

After the confrontation, talks took place between protesters and the police regarding the delivery of the letters. The police also apologised for using water cannon.

A declaration was read before the protesters dropped their letters into boxes, which were left outside the Grand Palace to be collected by the Royal Household Bureau.

“If the king can talk to the people who love him, he must also talk to the people who do not all the same ... The three demands from the protesters are the utmost compromise," the declaration read.

"When you hear all the flattering praise from the people, you must also hear fearless criticisms and suggestions all the same."

The Thai king has been caught in an unprecedented political movement that challenges the powers of the monarchy – a highly revered and legally protected institution in Thailand that has not been so openly questioned until recently.

"If 'love them all the same' is true, the king must receive letters from us, who are equally human beings as those in yellow shirts shouting 'Long Live the King'," said a protester organiser on Saturday.

"We are simply citizens who are telling the truth ... spoken by people with good intentions, not sweeping it under the carpet, telling lies or uttering sweet words of praise to blind some people to real problems."

When asked last week to comment on the protests, the king first said he had no comment before quickly adding "we love them all the same" three times and that "Thailand is the land of compromise".

The rally on Sunday is part of a series of protests that have occupied Thailand for several months. The gathering began in the afternoon at the Democracy Monument, a historic place in the capital city that commemorates Thailand's transition from absolute monarchy to constitutional monarchy in 1932.

Protesters are also calling for an end to the rule of Prayut Chan-o-cha, the current prime minister and former army chief who came to power six years ago. They are also demanding a more democratic Constitution and reform of the powerful monarchy.

More than 9,000 police officers were deployed on Sunday around the Democracy Monument, the Grand Palace and the Government House prior to the rally, according to Deputy Metropolitan Police Commissioner Piya Tawichai.

Authorities also warned that protesters are not allowed to hold public gatherings within 150m of the Grand Palace or any royal residences, and that any violation would result in legal action.

"It's our duty to maintain peace and order and to prevent incidents. We're also worried about people who join the protest. When they travel home tonight, it may not be safe because they'll do so in various directions while police officers may need to focus on certain areas and are thus unable to provide security thoroughly," Piya told reporters in a press conference on Sunday.