One is 'to show that there is depth in our leadership team', said Mr Lee on Monday.

'It's not just one person running everything but there are others who are making significant contributions and more than pulling their own weight.'

The other reason: 'It's a signal that a younger team is in charge, that we are looking ahead, moving forward.'

Commenting on Mr Teo's promotion to Deputy Prime Minister from Wednesday, Mr Lee said: 'Teo Chee Hean reinforces me. I'm 57, Chee Hean said he's 54, he's just three years younger than me.'

In moving up to be DPM, Mr Teo will also help him in broader policy matters, apart from defence and civil service matters.

Mr Teo will remain the Defence Minister and Minister-in-charge of the civil service. Singapore's other Deputy Prime Minister is Home Affairs Minister Wong Kan Seng, 62.

Mr Teo, a former President's Scholar and navy chief, also deserves to be promoted as he is capable of making a contribution beyond his current portfolios, said the Prime Minister.

'Especially during this economic crisis when we need good policies, good implementation and also good political work on the ground, I think Chee Hean can make a contribution in all three areas.'

Mr Teo entered politics in a 1992 by-election and was appointed immediately to the front bench. He has since held portfolios in such ministries as Finance, Environment and Education.

Read the full report in Tuesday's edition of The Straits Times.