A defiant David Cameron refused to back down yesterday over his controversial decision to describe migrants heading for the UK as a ‘swarm’.

Instead, the Prime Minister raised the stakes by issuing a new vow to stop illegal immigrants trying to ‘break into’ Britain.

Mr Cameron reacted to the crisis at Calais last month by referring to migrants as ‘a swarm of people’ – sparking acting Labour leader Harriet Harman to remind him he was talking about ‘people, not insects’.

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Strong words: The Prime Minister said many of those attempting to get into the UK were doing so for economic reasons

But yesterday, Mr Cameron insisted: ‘I was explaining that there are a large number of people crossing the Mediterranean and coming from the Middle East and coming to Europe... I do not think it does dehumanise people.’

But the Prime Minister risked a fresh row over his choice of language as he added: ‘What we can’t do is allow people to break into our country. A lot of people coming to Europe are coming in search of a better life, they are economic migrants and they want to enter Britain illegally.

‘And the British people and I want to make sure our borders are secure and you can’t break into Britain without permission.’

In a BBC interview, Mr Cameron defended Britain’s response to the refugee crisis, saying: ‘I made sure that we sent the Royal Navy flagship to the Mediterranean which has rescued thousands of people, saved thousands of lives.’

Generous: Mr Cameron believes the UK had been 'one of the most generous countries in Europe' for granting asylum to refugees fleeing persecution or danger

Controversial remark: Commenting on his use of the word 'swarm' the Prime Minister said: 'I was not intending to dehumanise'

And the Prime Minister reiterated plans to reduce the flow of legal migrants into the UK, including proposals for welfare restrictions for EU citizens coming to the UK.

He warned that UK benefits acted as a magnet for foreign workers, saying: ‘Our in-work benefits are incredibly generous and act as an additional draw because you can get something like £8,000 extra on top of your salary coming from Europe to work in Britain.

‘We need to reduce that draw to make our welfare system work better for us. We have had these circumstances in the last few years, we have created more jobs in Britain than the rest of the EU put together, so it’s not surprising people have wanted to come.’

Last night, Shadow Home Secretary Yvette Cooper said: ‘Cameron should apologise for his divisive language not defend it. You don’t call people a “swarm” – they are fathers, mothers, daughters, sons.’

She added: ‘Instead we need a humane and practical plan, starting with getting the UN High Commissioner For Refugees to assess people camping at Calais to make sure refugees get support, illegal travelling is prevented, and tackle the problems on the coast.’

Deterrent: Speaking on Radio 4's Today programme, the Prime Minister said: 'We need to reduce that draw to make our welfare system work better for us and to act as less of a draw for migrants coming in from Europe'