The Church of England has suffered a dramatic slump in its followers, shocking new figures show.

Between 2012 and 2014, the proportion of Britons identifying themselves as C of E or Anglican dropped from 21 per cent to 17 per cent -- a fall of about 1.7 million people.

Over the same period, the number of Muslims in Britain grew by nearly one million, according to a survey by the respected NatCen Social Research Institute.

Former Archbishop of Canterbury Lord Carey warned last night that unless urgent action was taken, the Church was just 'one generation away from extinction'.

The number of Anglicans in Britain has dropped from about 10.3 million to 8.6 million, and will raise fresh fears over the future of the Church of England, which has been in decline since the 1960s.

Lord Carey, who has warned before about dwindling congregations, said: 'These figures are a call to urgent mission. I have no doubt at all that the Archbishops, together with the whole leadership of the Church of England, are doing all they can to reverse this trend.'

The current Archbishop, Justin Welby, has also called for the decline to be tackled and is introducing measures to streamline the Church and strengthen its leadership.

Peter Brierley, a former Government statistician who advises religious groups, said: 'It is very serious for the Church of England and they know it.

'The problem is that it has a lot of elderly members, but when they die off there are not enough younger people to replace them.'

Figures from the survey going back more than 30 years paint an even bleaker picture, with the Church haemorrhaging nearly eight million followers in that time.

In 1983, 40 per cent of the British population -- or 16.5 million people -- identified themselves as Anglican or C of E, but this number has now more than halved.

The current Archbishop, Justin Welby, has also called for the decline to be tackled and is introducing measures to streamline the Church and strengthen its leadership

Alarmingly for Church leaders, the worst losses have come over the past decade, with about 4.5 million fewer people affiliating themselves to the C of E or Anglicanism between 2004 and 2014. In contrast, those who describe themselves as Muslim have jumped from 3.2 per cent of the population -- equivalent to 1.5 million -- in 2012 to 4.7 per cent or 2.4 million in 2014. The only Christian denomination that has remained relatively stable between the 1980s and today is Catholicism -- numbers have dipped slightly from ten per cent to eight per cent.

Mr Brierley said the Roman Catholic Church had benefited from the influx of immigrants in recent years, particularly those from Eastern Europe. He added: 'It is not just Poles. Many others are joining the Church when they come here, from Filipinos to Portuguese. There are seven different Catholic churches just for Croatians in London.'

A category called 'Other Christian' has also remained steady, boosted by the rise of largely black congregations attending Pentecostal 'mega-churches'.

Naomi Jones, of NatCen, said one explanation for the Anglican decline is that fewer people see Christianity as being an important part of their British identity.

A C of E spokesman said: 'The survey figures are based on a less reliable sample than in the National Census in 2011, which showed almost 60 per cent of those questioned self-identified as Christian.'

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