Orthopaedic surgeon Ang Swee Chai is due to be inducted into the Singapore Women's Hall of Fame on Friday for her work in Palestinian refugee camps in the 1980s and 1990s.
However, she is struggling to obtain the clearance she requires to enter the country.
Dr Ang, 67, is the widow of alleged communist activist Francis Khoo. She has spent the last 39 years overseas but has not been able to secure a special travel document to come to Singapore from London, where she lives.
She needs the special papers because she holds both British and Singapore citizenship and does not want to give up either.
"I can come into Singapore with a British passport, but unless there is assurance that the Immigration and Checkpoints Authority (ICA) will not strip me of my Singapore citizenship, I must not risk it," she told The Straits Times in an e-mail.
"The ICA has pointed that out to me... I stand to lose my citizenship if I do so," she added.
Dr Ang is due to be feted at a gala dinner at the Shangri-La Hotel. The Women's Hall of Fame is administered by the Singapore Council of Women's Organisations (SCWO) and counts among its 133 honourees women such as war heroine Elizabeth Choy, who helped British internees during World War II.
Dr Ang returned to Singapore once, in 2012, on a Singapore Travel Document, to bring home her husband's ashes but a Ministry of Home Affairs (MHA) spokesman said it was a "one-off" approval based on compassionate grounds.
Mr Khoo lived in exile after he fled Singapore in 1977 to avoid questioning by the Internal Security Department during a security sweep targeted at communists. He died in 2011 in Britain.
An MHA spokesman said the Government does not allow citizens to hold dual citizenship, and will not issue travel documents if they have not renounced their foreign citizenship. She said Dr Ang's 2012 travel document was issued with a "clear understanding that she would resolve her dual citizenship status expeditiously".
Since then, ICA has reminded Dr Ang to do so four times - the last reminder was last month, on Feb 4, a spokesman said. "ICA will process her request for such a document, once she shows proof she has started the process of renouncing her British citizenship."
But in an e-mail to SCWO, Dr Ang wrote: "My right of abode and right to work as a surgeon in the UK is conditional on British citizenship."
SCWO general manager Selina Gan said: "We're always disappointed when an inductee cannot come to the induction dinner but, of course, they will still be inducted, and they will be represented by a relative or friend."