Many in their early 30s lack the confidence to take on the job, as they do not have sufficient exposure and have yet to become well-recognised individuals in society, added the party leader.
'And if they are not quite ready, then when they come in, even their grassroots leaders will say, 'I have been here 20 years, you're 25 years old',' he said.
Singling out Holland-Bukit Timah GRC MP Christopher de Souza, who is the youngest MP, Mr Lee said the 31-year-old lawyer is a 'good MP' who has an 'extra load on him' because of his age.
He said: 'And we must make an extra effort to bring in more people like Chris de Souza.'