Conservative MP Esther McVey has been promoted from minister for the disabled to employment minister.
She was said to have "looked happy" as she left Downing Street.
Northern Ireland minister Mike Penning has just driven into Downing Street
The Conservative minister for the disabled Esther McVey has just walked into Downing Street.
She said there was "no news yet."
Fisheries minister Richard Benyon will leave his position and return to the backbenches, the Conservative MP said.
On back benches! 3 and half really fun years with much achieved. Really appreciate time working with outstanding Ministers and Officials
Nick Clegg said "other experience" was required in the run-up to the independence referendum as he sacked Michael Moore from his post as Scottish secretary.
As we discussed when we spoke on Friday, I believe we now need to draw on different experience in the final year running up to the referendum itself and I am keen that just as we have benefited from your formidable skills over the past three years that we take advantage of other experience within our ranks during this period.
Mr Moore replied:
This has been, and will continue to be, a hugely important time in Scottish politics and that has made it a challenging and rewarding time to be Secretary of State for Scotland.
In leaving the Scotland Office I am pleased that Alistair will be succeeding me. As a good friend and long-time colleague, I believe he will do a superb job. I wish him all the best.
The Prime Minister has said he will confirm ministerial appointments on Twitter - the first being Alistair Carmichael as the new Scottish Secretary:
Liberal Democrat Michael Moore has been replaced as Scottish Secretary by the party's chief whip Alistair Carmichael, Press Association sources confirmed.