Working dads will start getting an extra week of paternity leave fully paid for by the Government, bringing the total to two weeks.

This is in recognition of the important role they play in every family, said Prime Minister Lee Hsien Loong during yesterday's National Day Rally speech.

"Fathers play a very important role in bringing up children," he said. "You have to do your part. If it is just the mother's responsibility to care for and raise the children, I think (she) will decide enough is enough."

To give employers time to adjust, firms will join the new scheme on a voluntary basis for now.

"We will implement this, but the companies have to agree to give the leave," he said. "So we will not force the companies, for a start."

The civil service, he added, will be one of the first to offer new fathers this extra week.

Paternity leave was first introduced in 2013, as part of the Government's enhanced Marriage and Parenthood Package.

Civil servant Alan Shui, whose son Alzander was born in February, welcomed the news. "When your wife gives birth, she will be very tired, so it is better if you have another pair of hands to help," said the 26-year-old.

Minister in the Prime Minister's Office Grace Fu, who oversees population issues, said details will be announced later this week, but noted that the Government will encourage the "more enlightened" companies first.

"Critical mass will set the tone," she said. "The labour market is competitive and we hope that with some big employers leading the way, others will have to follow in order to attract and retain talent."

She said that the enhanced package of benefits - including the bumped-up Baby Bonus - is not so much to increase Singapore's fertility rate, but a recognition of the high costs of raising a child here.

"What we are doing is to create a supportive environment, from financial support to childcare arrangements, to arrangements in the office," said Ms Fu.

Linette Lai and Rachel Au-Yong