Media playback is unsupported on your device Media caption Labour Deputy Leader Harriet Harman outlines the party's "new approach" to immigration

Labour has said it backs further restrictions on migrants' ability to claim benefits as a sign it understands public concerns about immigration.

Deputy leader Harriet Harman said her party was considering requiring migrants to "earn the right" to contributory benefits.

Ms Harman also insisted there was "no wobble" over Ed Miliband's leadership.

Meanwhile, Boris Johnson has said the UK should leave the EU unless it can get fundamental changes on immigration.

Ms Harman said her party shared public unease about the impact of immigration on UK workers' pay and pressure on public services.

Labour's narrow victory in the Heywood and Middleton by-election, where it held off UKIP by less than 700 votes, has increased the pressure on Mr Miliband to respond to Nigel Farage's party.

UKIP leader Nigel Farage told the BBC he expected more Conservatives, as well as Labour MPs, to be tempted to join his party - since their parties were "utterly disconnected" from the public and "not being straight" on Europe.

'No chance'

Amid calls from one former Labour MP for Mr Miliband to stand down, Ms Harman told the BBC that there was "absolutely" no chance of a change at the top.

"We are not going to have a wobble or a leadership change," she told the Andrew Marr show.

The Observer reports Labour is planning a series of announcements on immigration in the coming weeks amid calls for it to do more to address UKIP's challenge in the north of England.

Media playback is unsupported on your device Media caption London Mayor Boris Johnson said the UK needs a "points-based system" akin to Australia and America to control immigration

In an article for the paper, Mr Miliband said the ability of new migrants to claim benefits must be based on the principles of "contribution, responsibility and fairness".

Labour has already adopted tougher rhetoric on immigration in recent times, backing an extension of the time EU migrants must be in the UK before claiming out-of-work benefits to six months.

It is now hinting at action over the length of time migrants have to pay national insurance before being able to claim certain benefits, such as elements of jobseekers allowance, after this initial period.

Sources close to Mr Miliband told the newspaper that the announcements would go further than existing plans. Measures are expected to include language tests on migrants to ensure those applying for public sector jobs have a level of proficiency as a condition of being taken on.

Ms Harman acknowledged UKIP had exploited people's "disconnection" from the political process and "despair" about their future economic prospects, but insisted it did not have the answers.

'New approach'

Labour, she said, must talk more about immigration and demonstrate that it was not just listening but "shared" people's concerns about its impact on jobs, pay and public services.

As part of what she described as a "new approach", Ms Harman said Labour backed stopping serious criminals from entering the country and deporting any foreign citizen who commits a serious crime while in the UK, even those from other EU member states.

Media playback is unsupported on your device Media caption UKIP's first elected MP Douglas Carswell said the Tories run along a "defunct retail model"

The Conservative Mayor of London Boris Johnson said the UK government should seek to qualify the right of migrants from existing EU members to come to the UK to work.

While London had benefited hugely from immigration, he said it was "reasonable" to toughen controls and a US or Australian-style points system was needed to know the numbers coming in.

'Worse off'

As part of a future renegotiation of the UK's membership, he said the Conservatives should be prepared to walk away from the EU if it could not get the changes it wanted, telling Andrew Marr there was "nothing to fear" from such a move.

"If we can continue to have access to European markets and if we can continue to be part of the great free trade zone, then there is a viable future for our country with a different arrangement."

UKIP leader Nigel Farage has suggested his party might be prepared to support a minority Conservative government, in the event of a Hung Parliament after next year's election, if it agreed to accelerate plans for an EU referendum.

He told Daily Politics the "uncontrolled flow of mass labour" had made millions of people worse off and the public could not wait until 2017 - the date earmarked by David Cameron - for a say on Europe since an extra million migrants would have come to the UK by then.

However, Douglas Carswell - who became UKIP's first elected MP on Friday - downplayed one opinion suggesting it may win up to 25 seats at the next election, saying this was "bravado talk".

The full list of candidates announced so far, in alphabetical order by surname, is: