A Downing Street spokesperson said:
The Prime Minister regrets that Baroness Warsi has decided to stand down and is grateful for the excellent work that she has done both as a Minister and in Opposition.
Our policy has always been consistently clear - the situation in Gaza is intolerable and we've urged both sides to agree to an immediate and unconditional ceasefire.
More top news
Swansea striker Bafetimbi Gomis has been stretchered off the pitch after collapsing during his side's clash with Spurs at White Hart Lane.
ITV News has obtained a video statement made by a former Royal Marine who was later killed fighting against Islamic State in Syria.
A recent three million year-old discovery in Eithiopia has pushed the timeline of human history back 400,000 years.