The Labour party today launched its campaign for Britain to remain in the European Union, saying that the Paris terror attacks showed the need to "stand shoulder to shoulder" with European partners.
The Conservative government has promised an in-out referendum by the end of 2017, with recent polls showing the public split neck-and-neck on the issue despite all the main parties campaigning to stay in.
Former interior minister Alan Johnson launched his party's campaign to stay in the 28-member bloc in Birmingham, central England, arguing that Britain would be less safe on its own.
"The first duty of any government is to keep our country safe and I firmly believe that leaving the EU would fail that test," he said.
"The lesson from Paris is clear: to tackle terrorism we must stand shoulder to shoulder with our allies in Europe. The security of Britain is inextricably linked to staying in Europe.
Britons will be asked whether they want to "Remain" in the bloc or "Leave" after the electoral commission ruled that a "Yes" or "No" question could favour those who want Britain to stay in the EU.
Labour has been a solid supporter of the EU since the premiership of Tony Blair, but that was thrown into doubt with the election of veteran leftist Jeremy Corbyn as party leader in September.
He had previously opposed the bloc's free-market rules, but threw his weight behind the "Remain" campaign shortly after being elected.
Johnson also said that British workers, businesses, universities and scientists will all be "damaged and diminished" in the event of a "Brexit".
"There is nothing patriotic about condemning this country to isolation," he added.
Prime Minister David Cameron has pledged to campaign to stay in, but only if he secures EU reforms on issues such as welfare payments for migrants and the balance of power between Brussels and national parliaments.
The Labour campaign is separate to the cross-party, pro-EU campaign Britain Stronger in Europe.
They will be opposed by Leave.EU, which has the backing of UK Independence Party chief Nigel Farage, and Vote Leave, which is supported by eurosceptic Conservative and Labour MPs and business figures.
