With 10 days to go before Britons vote on whether to remain a member of the 28-country bloc, polls show that a slim early lead for the "In" campaign has evaporated in recent weeks, leaving public opinion split roughly down the middle.

Maier said he had been scrutinizing the polls closely and believed it was now neck and neck between the two campaigns.

"Absolutely I'm worried, because it's clear it's going to be close and I really want to see the outcome that I believe is best for Britain," he told Reuters on the sidelines of an international business festival in Liverpool, northern England.

Maier has openly campaigned for Britain to stay in the EU, including appearances alongside Prime Minister David Cameron. He argued the bloc gives Britain international influence, supports research and development and supports investor confidence.

Rival "Out" campaigners say that leaving the EU would grant Britain greater control over its economy and the freedom to cut its own international trade deals.

Maier criticized the campaign so far, saying it had become a "media-rich, hysterical debate". He said there had been too much focus from both sides on arguments being made by politicians, and not enough of the views of business and other communities.

"The campaign unfortunately has just become too polarized - it hasn't provided that calm rational debate that's needed," he said.

(Reporting by William James; editing by Stephen Addison)