His Majesty the King sent a message of goodwill to the president of Singapore, Tony Tan, as the country marked 50 years of independence on Sunday.
The King's message reads as follows:
"On the occasion of the 50th anniversary of the Republic of Singapore's National Day this year, I take great pleasure in extending to Your Excellency and the people of Singapore my goodwill and best wishes for your country's well-being and prosperity.
"This year is also momentous for our two countries as it marks 50 years of diplomatic relations between Thailand and Singapore.
"I am confident our cordial relations and cooperation, which have been based on mutual respect, goodwill and sincerity, will strengthen and develop further in the future.''
Prime Minister Prayut Chan-o-cha led a delegation of officials to Singapore on Sunday to take part in the celebrations to mark the 50th anniversary of Singapore's National Day.
The prime minister left the military airport in Don Mueang in the morning, and was returned to Thailand just before midnight Sunday.
Maj Gen Weerachon Sukhondhapatipak, a deputy government spokesman, said Gen Prayut took part in the event at the invitation of Singapore's Prime Minister Lee Hsien Loong.
Gen Prayut went to congratulate Singapore on its 50th National Day anniversary and also the 50th anniversary of diplomatic ties, Maj Gen Weerachon said.
The countries have enjoyed a long and close relationship, Maj Gen Weerachon said, adding that Thailand was among one of the first countries to recognise Singapore's independence in 1965.
Thailand established diplomatic ties with Singapore about one month after the country declared its independence from Malaysia, the deputy government spokesman said.
He said Singapore and Thailand share a common aim of strengthening ties within the Asean community, and creating a balance of power between all the countries in the region.
Thailand intends to boost its long-standing partnership with Singapore in several areas including trade and investment.
Among Asean countries, Singapore accounts for the largest proportion of investment in Thailand and is Thailand's second largest trading partner in the region, Maj Gen Weerachon said.
Singapore's private sector has shown confidence in Thailand's economic principles and potential over the past several years, he added.