Consumer goods giant Unilever has warned Britain that that it will rethink bringing its billions of euros worth of investment into the country if the UK ends up leaving the European Union.

"We are very concerned about the overall competitiveness of Europe vis-a-vis the rest of the world," said Paul Polman, chief executive at the Anglo-Dutch group, in a media statement.

It comes as no surprise that Unilever, the consumer goods conglomerate that counts Ben & Jerry's and PG Tips tea among its portfolio of brands, is weighing up where it should plough its future investments following its disappointing 2013 results.

Turnover declined in 2013 after sales were hit by a slowdown in some emerging markets and weak growth in developed markets.

Unilever banks on developing and emerging markets for more than half of its sales, said annual turnover dropped 3% to €49.8bn (£41.1bn, $67.5bn), pulled down by foreign exchange rates and divestments.

Developed markets remained weak with little sign of any overall improvement despite the more positive macro-economic indicators in recent months, Unilever said in a statement on 21 January.

"2013 provides further evidence of the progress we are making in transforming Unilever into a sustainable growth company," said Polman.

"We have delivered another year of consistent underlying sales growth and margin expansion coupled with strong cash flow. This has been achieved despite significant economic headwinds and highly competitive markets and reflects the benefits of strong margin accretive innovations and active cost management.

"Looking forward, we anticipate ongoing volatility in the external environment and are positioning Unilever accordingly. Although the investments we have made over the last five years ensure that we are well placed, we are determined to make Unilever even more agile and to fund further growth opportunities by driving out complexity and cost."

Markets in Europe remained flat as the early signs of stabilisation in southern Europe were offset by slowing growth in northern Europe. Sales performance, whilst negative, was competitive.

Meanwhile, the UK delivered the 25<sup>th consecutive quarter of growth, the company added.

Chancellor George Osborne has already warned the EU that the UK and other countries will leave the bloc if it does not reform.

He said that if his and Prime Minister David Cameron's ruling Conservative party is re-elected in 2015, they will keep their promise to renegotiate the UK's EU ties before offering Britons an in/out membership referendum.

According to a number of recent polls, a slim majority said it would vote to leave the EU if it was given the chance.

"Our determination is clear: to deliver the reform and then let the people decide," said Osborne.

"It is the status quo which condemns the people of Europe to an ongoing economic crisis and continuing decline. And so there is a simple choice for Europe: reform or decline."