The number of overseas immigrants moving long-term to East Anglia has risen to almost 300,000 in the last 20 years, new figures have revealed.

The region was one of just two parts of the country where net migration rose in the last year, according to an Office of National Statistics report released yesterday.

Last night, a Suffolk MP described the rise as “unsustainable”, but insisted – ahead of access restrictions to the UK labour market being lifted for Romanians and Bulgarians in January – the figures would be “turned around”.

The report found that long-term net migration – the difference between the number of people emigrating and the number of immigrants arriving – totalled 281,000 between 1991 and 2012 in the east of England.

It was just one of two regions out of nine in England that saw an increase between 2011 and 2012, rising from 22,000 to 24,000. It fell in London by 27%, from 54,000 to 39,000.

Mr Gummer said: “In the last 20 years we have added almost two Ipswiches to the eastern region. This is a rate of growth that is unsustainable and shows how immigration got completely out of control over the last decade.

“We are beginning the task of turning around these figures and with further measures to be voted on I am determined to be part of that effort.”

The figures come amid growing concern that Britain will face a new wave of eastern European immigration when access restrictions to the UK labour market for Romania and Bulgaria are lifted on January 1 next year.

Mr Gummer added: “It is important to say people from Romania and Bulgaria can already come here – and on January 1 will be able to work without work permits – but we need to do an enormous amount to stop the benefit system becoming a draw.

“The Prime Minister is on the case to prevent that and I am confident there will be no repeat of the time when we were promised only a few thousand Polish people coming here and ended up with hundreds of thousands.”

Brian Finnerty, spokesman for NFU (National Farmers Union) East Anglia, said agriculture was “one sector that has benefitted from migrant labour”.

He said: “Migrant workers can offer employers crucial flexibility when they need it. For example, the picking and harvesting of fruit is seasonal and weather dependent.”

But he called on the government to reverse its decision to scrap the “extremely successful” Seasonal Agricultural Workers Scheme, under which farmers recruit low-skilled overseas workers to carry out short-term agricultural work.

Mr Finnerty added: “Migrants help the local economy and return home having learned new skills. It is very unfortunate it is ending.”

The new research follows official projections indicating the region’s population will rise by the fastest rate (19.5%) in the country between 2010 and 2030.

David Burch, director of policy at Essex Chambers of Commerce, said: “To some extent a low cost a labour force will help businesses but I am not sure it is healthy in the longer term as we need to ensure that we are developing properly skilled workers ready to enter the labour market at any level rather than being over reliant on migrant workers to fill some vacancies.”

An international long-term migrant is defined as “someone who changes their country of usual residence for a period of at least a year, so that the country of destination effectively becomes the country of usual residence”.