SINGAPORE - The red box in which founding prime minister Lee Kuan Yew kept his working documents was put on display at the National Museum of Singapore on Thursday.

It is part of the memorial exhibition on Mr Lee's life titled "In Memoriam: Lee Kuan Yew".

Education Minister Heng Swee Keat, who served as Mr Lee's principal private secretary from 1997 to 2000, wrote an essay last Tuesday - a day after Mr Lee's death - about how the red box symbolised his unwavering dedication to Singapore.

Red boxes have been used by British ministers to transport official documents. Singapore's early ministers also had red boxes, and Mr Lee had used his consistently through the years. Mr Lee's red box has the words "Government of Singapore" in gold on its front.

Prime Minister Lee Hsien Loong, who is Mr Lee's elder son, visited the National Museum of Singapore exhibition on Tuesday. The box is displayed together with other personal items used by Mr Lee, including his barrister wig he had after he was admitted to the Bar; and the Rolex Oyster Perpetual watch presented to him by the Singapore Union of Postal and Telecommunications Workers.

The exhibition is open daily from 10am to 8pm at the Glass Atrium on the second level of the museum until April 26. Admission to the exhibition is free. Hardcopies of the exhibition text in English, Mandarin, Malay and Tamil will be available from Saturday for visitors to take home.

More than 14,000 people have visited the exhibition since it opened on March 25, said the National Heritage Board in a statement on Thursday. Following the exhibition, the red box, along with other personal objects and parts of the memorial exhibition will be incorporated into the Museum's permanent galleries.