The Bush administration on Wednesday welcomed Tony Blair’s decision to withdraw nearly a quarter of the British troops in Iraq over the next few months, saying the move showed that in parts of the country “things are going pretty well”.

But although the British prime minister told parliament that the withdrawal of 1,600 troops would allow Iraqis to “write the next chapter in their history”, prominent Democrats in Congress said the move was a sign that Britain was now giving up on the US in Iraq and contrasted it with the surge in US troop numbers deployed to contain the violence in Baghdad.