Labour frontbenchers to launch pro-EU campaign
A group of senior Labour frontbenchers is planning to set up an "unashamedly pro-European campaign group".
It follows disagreements within the shadow cabinet over how to approach the EU referendum.
A handful of senior figures are already discussing hiring office space and seeking funding to launch their campaign as soon as possible.
David Cameron has promised a referendum on whether the UK should stay in the European Union before the end of 2017.
One member of the shadow cabinet told the BBC that Acting Labour Leader Harriet Harman was "panicking" about Labour being seen as "being tied to the Tory leadership" during the referendum campaign.
A spokeswoman for Ms Harman said it was important the party was "given room" to express different views after its election defeat.
The referendum - a Conservative election manifesto promise - has been causing Labour grief for some months.
The party opposed the idea during the election campaign, arguing a referendum would be destabilising for the UK.
But it changed its mind after losing in May.
Now there are two further dilemmas for the party.
Does it wholeheartedly and immediately become the voice for staying in the EU - before we know what new deal the Prime Minister has negotiated with Brussels?
And does it run the risk of being seen as too close to the Conservative leadership, assuming, as expected, David Cameron eventually advocates staying in?
Some within the party are nervous of a repeat of what happened after the Scottish independence referendum, where Labour and the Conservatives were on the same side of the argument, allowing the Scottish National Party to describe Labour as "red Tories" during the general election campaign.
UKIP finished second behind Labour in 44 seats at the general election and some within Labour fear sounding stridently pro European when so many of their former voters have been lured towards Nigel Farage's party.
But one shadow cabinet minister said: "We have got to get on with this. If we wait until October we will be playing catch-up.
"Labour has got to make an unashamedly pro-European case, with passion. We can't be trying to second guess the Tories.
"Let the Conservatives tear themselves apart and we can be on the side of the majority of people who want to stay in."
But a source close to the interim Labour leadership - which has the tricky task of holding the fort until a new leader is elected - said it was important the party as a whole, including those in the shadow cabinet, were given chance "to be honest and vocal, and yes, at times, that will be uncomfortable."
"We want to encourage reflection at the moment, that is part of the healing process," the source said, adding "this isn't so much about nerves about the Tories, more that there are plenty of people within the party who are well aware of how well UKIP has done."
Some senior figures worry that after spending years trying to persuade constituents they understand why many are worried about immigration, now is not the time, weeks after the election, to be seen jumping up and down with pro European zeal.
Giampi Alhadeff, the Chairman of the Labour Movement for Europe, acknowledged that some within the party were nervous about being seen as stridently pro-European right now.
"It is understandable. There is a lot happening at the moment with the leadership race and we have just suffered a massive defeat. But we should pin our flag to the mast and do it now, it is important for Britain that we say we are better off in the European Union," Mr Alhadeff told the BBC.
He acknowledged he had "heard the argument" within the party about the supposed parallels with the Scottish independence referendum and the potential consequences for Labour afterwards, but disagrees with it.
"The problem for us in Scotland predates the referendum. And, more to the point, the EU referendum is the most important decision this country will make in a generation."
The Labour Movement for Europe is setting up what it is calling its "Westminster Parliamentary Group" later this month, with a reception in Westminster.
They hope to have recruited about 50 MPs to the cause by then.
For a party with 232 MPs, it is an insight into two other things.
Firstly, it is not just the Conservative Party that is subjecting itself to long, internal discussions about the European Union.
And secondly, the legacy of a crushing defeat at the general election has left a party nervous, unsure of itself and far from sure footed.