Shadow Business Secretary Chuka Umunna has said he doesn't think Boris Johnson's comments about returning British extremists are "sophisticated, sensible or responsible".
Labour dismissed accusations they had failed to capitalise on voters' disillusionment with the Government at the European and council elections, dubbing their wins "a very good set of results".
Shadow Business Secretary Chuka Umunna told Good Morning Britain Labour had won "over 25% of the vote", a growth of 9% on the last round of European elections.
"We have seen our tally of MEPs go up from 13 to 18. We're expecting to get another couple on top of that. So that is a really good set of results on top of a good showing in the local elections."
Today's appearance from Pfizer bosses before MPs "confirms many of the worst fears" about the proposed takeover of AstraZeneca, Labour have said.
Shadow Business Secretary Chuka Umunna told the BBC: "What we heard at the hearing today reinforces the grave concerns we have about this deal and confirms many of the worst fears of people in the business and science community in the UK.
"What do we know? They confirm that they will be cutting jobs. They confirm that there will be a cut in the spending of the combined merged entity. They've confirmed that the business, AstraZeneca will be split up, and they haven't ruled out selling off parts of it in the future.
Labour have hit out at Pfizer over their proposed takeover of AstraZeneca, saying the company's claims about its commitment to the UK are "not worth the paper they are written on".
Shadow Business Secretary Chuka Umunna issued a statement, saying:
"The assurances Pfizer has given Ministers are not worth the paper they are written on, given that Pfizer has since refused to rule out breaking up the AstraZeneca business and selling off parts of it in the future if this takeover proceeds."
Mr Umunna called on ministers to order a "proper, independent assessment of the takeover" to determine whether it is in the public interest.
Labour has hit out at the sale of Royal Mail, accusing the Government of leaving the taxpayer "disgracefully shortchanged".
Shadow business secretary Chuka Umunna said:
This report delivers a damning verdict on the Tory-led Government's botched Royal Mail fire sale, leaving the taxpayer disgracefully short changed by hundreds of millions.
At the same time, stamp prices have shot up by 30% and vital services have been put at risk at a time when families are already hit by a cost-of-living crisis.
We now know...far better value for taxpayers could have been possible had ministers adopted a different timetable for the sale.
The NAO could not be clearer: the inflexible timetable set by ministers for Royal Mail's privatisation resulted in the public losing out.
Shadow Business Secretary Chuka Umunna has said the Bank of England Governor should not be involved in big political matters after he said he did not support the view that a cap on banks' market share would improve competition.
Labour leader Ed Miliband is expected to pledge that he will refer high street banks to the competition authorities if his party wins the next general election in 2015, in a speech today.
Mr Umunna said “I think it’s not healthy for us to involve governors of the Bank of England in big political debates and I don’t want to drag him into that", the Times reports.
He also suggested Mark Carney had only expressed his view after being asked a "leading question".
"He was asked a leading question by a Conservative MP who put it to him whether crude market caps on the share of a market that banks have are a good thing or not.
"We’re not proposing a crude or arbitrary market cap, we’re proposing something that would be set by the independent Competition and Markets Authority". he added.
Competition among global banks is good for small businesses and will provide better rates on loans taken out by small to medium enterprises, the shadow business secretary told Daybreak.
Chuka Umunna said there was "a large degree of consensus" on the need for more competition among multi-national banks like HSBC and Barclays.
The shadow business secretary Chuka Umuunna has confirmed the reports that Labour is to call for a cap on the size of British banks in an attempt to increase competition in the domestic market:
We're determined to reform banking so it better serves the real economy- a British Investment Bank and more competition in banking are key
It cannot be right that lending to almost 5 million UK businesses is concentrated in the hands of 5 High Street banks.
The shadow business secretary Chuka Umunna has told ITV's The Agenda programme that politicians should follow Nelson Mandela's example "and try and do politics differently in this country."
It wasn't just about what he stood for and what he achieved but it was also the way he did his politics.
I think we have a big problem in the way that we do politics in this country.
In many respects it's broken, it's too adversarial, it's very yah-boo, it's a bad thing sometimes to acknowledge agreement.
In some senses the easy part is celebrating what he did, I think the challenge he sets for us as politicians is actually to follow his example and try and do politics differently in this country.
Mr Umunna was joined on the panel by Sun columnist JaneMoore, comedian Dom Joly and Countryfile presenter Julia Bradbury.
The Agenda with Tom Bradby is on ITV at 10.35pm.
Get involved in the debate during the show on Twitter by following @agendaitv and using the hashtag #theagenda.