Complexities in the building of the National Stadium have pushed back the completion date for the $1.33 billion Sports Hub.

Most of the hub will be finished by April as originally targeted, but a few more weeks are needed for testing and certifying the stadium's retractable roof and moveable seating.

This, however, will not affect the stadium's first event which is being planned in June, Acting Minister for Culture, Community and Youth Lawrence Wong said in Parliament on Tuesday.

In response to Nominated MP Nicholas Fang's question on whether the 35ha facility will be completed on time, the minister added that the Sports Hub will have a phased opening of its facilities.

An indoor aquatic centre and outdoor water sports centre will be available for use from April. The consortium behind the project, Sports Hub Pte Ltd, will announce the hub's opening schedule and full calendar of events later this month.