Labour's Jeremy Corbyn has welcomed two upcoming by-elections as an opportunity to challenge the government.

Asked if his Labour leadership was "toast" if the party did not hold on to seats in Copeland and Stoke-on-Trent Central, he said it was a chance to set out its policies on the NHS and Brexit.

He told the BBC's Andrew Marr Labour would "fight very hard" to keep seats.

Unite leader Len McCluskey said Mr Corbyn remained "on a learning curve" as leader of the Labour party.

MPs quitting

Mr Corbyn's interview followed the resignation this week of Labour MP for Stoke-on-Trent Central Tristram Hunt, who is quitting as an MP to take a job at the Victoria and Albert Museum.

A by-election is also due after Jamie Reed left his Copeland seat to take up a position at the Sellafield nuclear power plant.

Mr Corbyn, who said media coverage of Labour had not been "very fair", said the by-elections were "an opportunity to challenge the government on the NHS, on the chaos of Brexit, the housing shortage, on zero hours contracts".

He was questioned about a ComRes poll that found 43% of people thought the Tories under Prime Minister Theresa May would do a better job of managing the NHS this winter compared with 31% who thought Mr Corbyn and Labour would.

But almost half of the 2,038 questioned, 47%, agreed the Red Cross was right to say the NHS was in a "humanitarian crisis".

There has been a renewed focus on the state of the NHS in the past week after figures showed more than four in 10 hospitals in England declared a major alert in the first week of the new year as they came under unprecedented pressures and Downing Street put pressure on GPs to open for longer hours.

Asked about the more positive showing for his opposite number, and expected strong challenges in coming by-elections Mr Corbyn said: "I think the more people see the reality of the under-funding of the NHS, of the hiving off and privatising of services, the outsourcing of NHS facilities, the more and more disappointed and angry they are going to get."

Healthcare, social care and mental health services were under-funded in the current government, and that was putting a "massive strain" on Accident and Emergency departments, he said.

Labour would stop cuts in corporate taxation and the top rate of tax to keep £70bn for the Treasury, he said, and use that money to stop cuts to NHS services and to invest in social care.

'Seem competent'

Image copyright PA Image caption Len McCluskey said Labour MPs, Corbyn included, were grappling with the "changing nature" of their party

Len McCluskey, who is seeking re-election as his union's general secretary, told the BBC's Pienaar's Politics that leading Labour was still Mr Corbyn's "challenge" following his re-election in September.

"I think he's a decent man and I think he's putting forward really excellent policies at the moment. But there are huge challenges, now it's up to Jeremy to try to rise to those," he said.

Mr McCluskey said he didn't speak to Mr Corbyn that often "but when I do have access to leadership team they're very open and seem fairly competent to me".

Labour MPs are on a "learning curve" to "recognise the changing nature of Labour", he said, adding "Jeremy's on a learning curve to become a leader. He's still on that learning curve. I think he's getting better and I think he speaks to an awful lot of people, because he's an incredibly decent man. But it's his challenge."

Mr McCluskey has been accused by one of his Unite leadership rivals, regional official Gerard Coyne, of putting Westminster "power games" ahead of the union - a charge he denied.

Mr Coyne told Pienaar's Politics that whether someone was a supporter of Mr Corbyn or not had become an "obsession". More important was protecting Unite's members in the changing economy, he said.

Immigration questions

Shadow chancellor John McDonnell told Sky News it had been a "pretty good" week for Labour, despite critics' claims of "muddled" policies on high pay and migration.

Labour has faced questions recently about its position on the free movement of people, with Mr Corbyn being urged to back a change in the rules to allow migration numbers to be reduced.

Mr Corbyn said the UK should not "cut ourselves off completely" after leaving the EU, saying free movement would be a factor in negotiations over single market access.

Shadow foreign secretary Emily Thornberry said Labour was not going to "die in a ditch" for the sake of the continued free movement of labour and that there would have to be new rules after Brexit.

Speaking to ITV's Peston On Sunday, she said: "If we're leaving the European Union then we need to make sure that we have fair rules and properly managed migration but it's all subject to negotiation because our economy comes first."