Owner of Virgin Media plans a 500,000 pounds donation to UK's 'In' camp

(Reuters) - John Malone's cable company Liberty Global , which also owns Virgin Media, is evaluating a potential contribution of up to 500,000 pounds ($724,550) to a campaign to keep Britain in Europe.

The company is evaluating a contribution to the "Britain Stronger In Europe" campaign because of the "uncertain macroeconomic impact" that a UK exit from the EU could have on business and consumers, said Manuel Kohnstamm, chief corporate affairs officer at Liberty Global.

Citi , Goldman Sachs , JPMorgan and Morgan Stanley have already donated six-figure sums to the Britain Stronger in Europe campaign group, sources have said, as some of the world's biggest banks fear the impact on their UK operations of a British exit.

The campaign for Britain to leave the European Union saw its lead narrow slightly over the rival "In" campaign, according to a weekly online poll published by opinion poll firm ICM on Tuesday.

Most economists reckon leaving the EU would deal a blow to the British economy, with a hefty current account deficit - 7 percent of GDP in the last quarter of last year - leaving Britain vulnerable to any pull-back in investment flows.

($1 = 0.6901 pounds)

(Reporting by Kate Holton in London and Shivam Srivastava in Bengaluru; Editing by Sandra Maler)