LONDON (Reuters) - JPMorgan <JPM.N> said on Friday it saw a lead for the "Out" campaign in Britain's European Union referendum, according to an analysis of opinion polls.

"Our attempt to clean up the polls for methodological issues suggests a lead for leave in the 3-5 percent range at the time of writing," researchers said in a note.

"The swing toward leave appears to have accelerated as we moved into the period when we would expect status quo bias to show," they added, while warning that it was "now unlikely" that polls would offer clear guidance on the outcome.

(Reporting By Freya Berry; Editing by Catherine Evans)