The PM said the he had no plans to legislate, although he hinted ministers would not stand in the way of MPs attempting to introduce a backbench Bill.
Meanwhile, Home Secretary Theresa May echoed Culture Secretary Maria Miller earlier this week in suggesting a more limited reduction to 20 weeks.
More top news
The family of a man found dead in a park in Basingstoke say he will be 'sadly missed'. Jason Williams was found on Tuesday morning.
Thursday evening's weather for the west of the region
Thursday evening's weather for the east of the region