Labour leader Ed Miliband described yesterday's murder of a soldier in Woolwich as “an act of complete cowardice”.
Mr Miliband spoke to Prime Minister David Cameron today about the killing, after cutting short a visit to Germany to return to London.
He said the opposition was offering its "full support" to the Government in its response to the outrage
In a televised statement, Mr Miliband said: "This was an appalling and horrific murder and all of my condolences are with the families and friends of the victim, and indeed with our troops because they serve incredibly bravely all around the world and they've seen one of their own murdered in an act of complete cowardice.
"There are people who try to divide us with acts like this. They've tried it before in London and they've failed and they will always fail.
"There will be people who try to use events like this to divide us and they will fail too.
"They will fail because the British people are united across different faiths, different religions, different backgrounds, in their abhorrence of this and in values of decency and tolerance. That is the true character of the British people and that's why this terror will lose and will fail.
"We are a united country, not a divided country and anyone who tries to divide us will not succeed."
Asked if Mr Cameron was right to tell soldiers they can continue to wear their uniforms in public, Mr Miliband said: "The Government has our full support in the actions they are taking. We stand united as an opposition with the Government in the measures they are taking in response to this crisis. That's what I said to David Cameron when I spoke to him earlier on today.
"I think it is right that troops continue to wear their uniform. One of the ways we must ensure that terror doesn't win is by us going about our normal business."