Shadow Foreign Secretary Douglas Alexander said:
On the same day that top British business leaders fired a warning shot across the bows of the Prime Minister, a senior White House official has also signalled concerns about the possibility of Britain leaving the EU.
There is today a real risk of Britain sleepwalking towards exit because of a Prime Minister motivated more by the need for party unity than by the interests of the country.
More top news
There will be patchy light rain across the UK, but sunny spells in the west.
Research conducted on behalf of Facebook shows women face a number of hurdles when it comes to launching a start-up.
The 650-feet long hole emerged after a water main burst near the 14th-century Ponte Vecchio bridge.